If you have paid for home improvements such as solar panels, a heat pump, or a new boiler and the work is faulty, incomplete, or not as described, you have legal rights to seek a remedy. Knowing the correct process to complain about an installer in the UK can save you time and stress.
To complain about an installer in the UK, first follow their written complaints procedure within eight weeks. If unresolved, escalate to the relevant ombudsman or scheme (e.g., MCS for renewables) at no cost. Expect a decision in 12 to 16 weeks (GOV.UK, 2026).
- Follow the installer's written complaints procedure first under the Consumer Rights Act 2015.
- Send your complaint in writing and keep a copy for your records.
- The installer has eight weeks to respond with a final decision or deadlock letter.
- Escalate to MCS Consumer Protection Scheme for solar panels and heat pumps.
- Expect an ombudsman decision within 12 to 16 weeks at no cost (GOV.UK, 2026).
- The quickest route to a resolution is your installer’s own complaints procedure
- If the installer refuses to fix the problem, escalate to the relevant ombudsman or scheme
- Quick numbers typical complaint timelines and costs
- You can complain about an installer who is not registered with any scheme
- How to verify an installer’s certification before you complain (or hire)
- The direct answer to “complain installer uk” – your step-by-step plan
- What to include in your complaint letter to maximise your chances of success
- When to seek legal advice or involve the Energy Ombudsman
The quickest route to a resolution is to follow your installer’s own complaints procedure in writing. If that fails, you can escalate the issue to a relevant ombudsman or certification scheme at no cost to you, and in most cases you can expect a decision within 12 to 16 weeks (GOV.UK, 2026).
The quickest route to a resolution is your installer’s own complaints procedure
Before you escalate a complaint to an ombudsman or regulator, you must first follow the installer’s own written complaints process. Under the Consumer Rights Act 2015, all traders are legally required to have a complaints policy and to handle complaints fairly (Consumer Rights Act 2015).
Check your contract or the installer’s website for their complaints policy. Send your complaint in writing, either by email or letter, and keep a copy for your records. Your written complaint should include your reference number (if you have one), a clear description of the problem, and what you want the installer to do to put it right. The installer has eight weeks to respond with a final decision or a “deadlock letter” that confirms they cannot resolve the issue (Citizens Advice, 2026).
If the installer refuses to fix the problem, escalate to the relevant ombudsman or scheme
If the installer does not resolve your complaint within eight weeks, or if they send a deadlock letter, you can escalate the issue to the relevant ombudsman or certification scheme. Each scheme covers different types of work.
For MCS-certified installations such as solar panels, heat pumps, and biomass, escalate to the MCS Consumer Protection Scheme, which is administered by the Chartered Trading Standards Institute. For Gas Safe registered work, such as boilers and gas fires, escalate to the Gas Safe Register complaints team. For electrical work under Part P of the Building Regulations, such as wiring and EV chargers, escalate to NICEIC or NAPIT if the installer was registered with them. The ombudsman or scheme will review the case and can order the installer to fix the work or pay compensation (MCS, 2026; Gas Safe Register, 2026; NICEIC, 2026; NAPUT, 2026).
Quick numbers typical complaint timelines and costs
| Detail | Value |
|---|---|
| Time for installer to respond to initial complaint | 8 weeks (legal maximum under Consumer Rights Act) |
| Time for ombudsman to issue a decision after escalation | 12–16 weeks (MCS Consumer Protection Scheme) |
| Typical cost of a complaint to the ombudsman (homeowner) | £0 (free to the consumer) |
| Typical cost to the installer if complaint is upheld | Up to £25,000 (MCS scheme limit) |
| Percentage of MCS complaints resolved in favour of homeowner (2023 data) | 62% |
| Number of MCS complaints received in 2023 | 1,847 |
Source: MCS Annual Report 2023, GOV.UK, 2026, Consumer Rights Act 2015.
You can complain about an installer who is not registered with any scheme
If the installer is not MCS, Gas Safe, or Part P registered, you still have consumer rights under the Consumer Rights Act 2015 and the Consumer Contracts Regulations 2013. Your first step is the same: follow the installer’s own complaints process. If that fails, you can take the installer to the small claims court for claims up to £10,000 in England and Wales or £5,000 in Scotland (GOV.UK, 2026).
You can also report the installer to Trading Standards via the Citizens Advice Consumer Service. Trading Standards can investigate the installer and may take enforcement action if the installer is acting fraudulently or in breach of consumer law (Citizens Advice, 2026).
How to verify an installer’s certification before you complain (or hire)
Before you complain, or before you hire an installer, you should verify their certification. This will tell you which ombudsman or scheme to escalate to if needed.
Check the MCS Installer Database at mcscertified.com for solar, heat pump, and biomass installers. Check the Gas Safe Register at gassaferegister.co.uk for boiler and gas appliance installers. Check NICEIC (niceic.com) or NAPIT (napit.org.uk) for electrical installers. All certified installers must display their registration number on their website, van, and paperwork. If the installer cannot provide a valid registration number, they are likely not certified, and you should not hire them (MCS, 2026; Gas Safe Register, 2026; NICEIC, 2026; NAPUT, 2026).
Your step-by-step plan
- Write to the installer in writing, clearly describing the problem and what you want them to do.
- Wait up to eight weeks for their final response or deadlock letter.
- If they refuse or fail to respond, escalate to the relevant ombudsman or scheme (MCS, Gas Safe, NICEIC/NAPIT) – this is free for you.
- If the ombudsman cannot help, take the installer to the small claims court.
- Report the installer to Trading Standards if they are not registered or are acting fraudulently.
Source: GOV.UK, 2026, MCS, 2026, Citizens Advice, 2026.
What to include in your complaint letter to maximise your chances of success
A well-written complaint letter gives the installer a clear understanding of the problem and what you expect. Include the following details:
- Your full name, address, and contact details.
- The installer’s name, address, and registration number (if known).
- A clear description of the problem: what was installed, when, and what is wrong.
- Copies of all relevant documents: contract, invoice, photos, any previous correspondence.
- What you want the installer to do: fix the work, refund, or compensate.
- A deadline for their response (for example, 14 days).
Source: Citizens Advice, 2026, Which?, 2026.
When to seek legal advice or involve the Energy Ombudsman
If the installer is not covered by MCS, Gas Safe, or a Part P scheme, the Energy Ombudsman may still handle complaints about energy-related installations such as heat pumps and solar panels, provided the installer is a member of the Ombudsman Services. Check the Ombudsman Services website at ombudsman-services.org to see if the installer is a member (Ombudsman Services, 2026).
For claims over £10,000, or if the installer has gone bankrupt, you may need to consult a solicitor specialising in consumer law. Legal aid is not available for most installer complaints, but you can get free initial advice from Citizens Advice or a Law Centre (GOV.UK, 2026; Law Centres Network, 2026).
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Frequently Asked Questions
You have up to six years from the date of installation to make a claim under the Consumer Rights Act 2015, but you should act quickly. Ofgem advises contacting the installer within 30 days of noticing the fault for the best chance of resolution.
First, follow the installer's own written complaints process. If unresolved after eight weeks, escalate to the MCS Consumer Protection Scheme, administered by the Chartered Trading Standards Institute, at no cost to you (MCS, 2026).
Yes. For Gas Safe registered work like boiler installation, follow the installer's complaints policy first. If unresolved, escalate to Gas Safe Register's complaints procedure or the relevant ombudsman (Gas Safe Register, 2026).
A deadlock letter is a final written response from the installer stating they cannot resolve your complaint. Citizens Advice explains this letter allows you to escalate the issue to an ombudsman or certification scheme (Citizens Advice, 2026).
Escalating a complaint to an ombudsman or certification scheme like MCS or Gas Safe Register is free for consumers. GOV.UK confirms you will not be charged for the ombudsman's review (GOV.UK, 2026).
Include your reference number, a clear description of the problem, and what you want the installer to do to fix it. The Energy Saving Trust recommends keeping copies of all correspondence for your records.
Most ombudsman decisions are made within 12 to 16 weeks after you submit your case. GOV.UK states this timeframe applies to schemes like the MCS Consumer Protection Scheme (GOV.UK, 2026).
