How to complain about a TrustMark registered business

TrustMark is the Government Endorsed Quality Scheme covering work carried out in or around homes². Registered businesses must offer a minimum two-year guarantee on any works carried out, subject to terms and conditions³, and for ECO-funded measures there is a minimum 25-year guarantee on certain measures alongside the two-year work warranty⁴.

TrustMark explained and the trades it includes

TrustMark is the Government Endorsed Quality Scheme which covers work a consumer chooses to have carried out in or around their home². It covers domestic work only⁷, and firms register through Scheme Providers, industry bodies that run their own complaint and guarantee arrangements under the TrustMark Framework Operating Requirements⁸. Registration also gives firms access to government funded installation work², which is why so many grant-funded insulation and heating jobs are delivered by TrustMark registered businesses. For example, all innovation measures under ECO4 Innovation must be lodged with TrustMark or an equivalent and delivered by TrustMark registered businesses⁹.

For householders, the practical benefits of using a registered business include government endorsed quality, consumer protection, the TrustMark online directory, work backed by guarantees, a customer charter, Trading Standards integration and verified consumer reviews¹⁰. Registration is not a guarantee that nothing will go wrong, but it does mean there is a structured route when it does. If your work was done by an OFTEC registered business under the PAS 2030 specification or through the TrustMark scheme and you have concerns about the standard of the work, OFTEC also accepts reports under its own complaints procedure².

Before hiring, TrustMark suggests getting a minimum of three quotes for any work¹⁰, and energy consumer advice recommends at least three quotes to understand your choice and ensure good value¹¹. There should be no premium for using a TrustMark registered business¹⁰.

Raising a complaint: each stage explained

TrustMark operates a three stage process for resolving complaints, updated in April 2026¹.

1. Contact the business and explain your concerns. Give the firm a chance to put things right, and keep a written record of what you report and when.
2. Escalate to the business's Scheme Provider. If you cannot reach a satisfactory resolution with the business, the next stage is to escalate the complaint to the Scheme Provider the business is registered with. Scheme Providers are responsible for the conduct of their registered businesses and must do their best to resolve disputes, possibly using independent alternative dispute resolution for complex cases⁸.
3. Bring it to TrustMark. TrustMark then reviews whether the Scheme Provider handled the complaint appropriately, correctly and in accordance with its dispute procedures¹.

There are limits on what the process can take on. TrustMark is unable to investigate a complaint that relates to a financial or commercial matter, because these are contractual matters between you and the business¹. The process also does not apply if the business was not registered with TrustMark at the time it did the work, if the business no longer holds an active registration or has ceased to trade, or if you or the business have instigated legal action¹. When you make a warranty or guarantee claim, have the details of what the problem is ready¹².

What TrustMark itself will and will not do

TrustMark's role in a complaint is deliberately narrow. Its own statement of its role is worth quoting exactly:

TrustMark does not investigate individual complaints or award compensation¹³. Consumers are not entitled to compensation specifically under the TrustMark Scheme from the Department for Business and Trade, TrustMark, Scheme Providers or registered businesses, unless legislation states otherwise⁸. A financial or commercial dispute, such as a disagreement about the price, sits outside the scheme entirely¹.

What TrustMark does do is oversight. All complaints, whether or not they fall within its remit, are considered as part of ongoing monitoring of Scheme Providers and registered businesses, with appropriate action taken if requirements are not met⁸. TrustMark carries out desktop monitoring and risk-based inspections of work lodged in its Data Warehouse¹⁴, and it has the right to suspend or remove registered businesses from the scheme¹⁰. So a complaint that cannot win you compensation can still cost a firm its registration.

Taking matters further: Ombudsman and Trading Standards roles

If the TrustMark route does not resolve the matter, other bodies may take it on, depending on what the work involved. For energy supply problems, the Energy Ombudsman is approved by Ofgem to deal with consumer complaints about energy bills, mis-selling, problems with energy supply and problems with switching supplier¹⁵. You can complain to the Energy Ombudsman if a problem you have reported is not fixed within 8 weeks, if you and the energy company cannot agree on a fix, if you receive a deadlock letter, or if you are not happy with the decision received¹⁶. You must have complained to the supplier already, and the Ombudsman only handles disputes involving suppliers trading in Britain¹⁷.

Ofgem itself does not directly get involved with complaints about energy suppliers or network operators, including heat network suppliers and operators, and does not investigate individual disputes¹⁸. In the third party intermediary market, multiple dispute resolution schemes co-exist and some firms sign up to several, which complicates the redress landscape for consumers.

For general home improvement disputes, Trading Standards is the route, and consumer advice services in each nation can take complaints about problems with services¹⁵. Be aware of what consumer codes do not cover: the NICEIC complaints process, for instance, does not extend to complaints relating to the way certified businesses run their business¹⁹, and CTSI does not approve, vet or endorse individual traders using its Trusted Payments app, nor guarantee the outcome of any project, warranty claim or Ombudsman decision²⁰. For a fuller map of the escalation route, see complaining about an installer.

Cover included with registered work: warranties and guarantees

The guarantee is the practical protection that registration buys. All TrustMark registered businesses are required to offer a minimum two-year guarantee on any works carried out, subject to terms and conditions³. For work funded under the Energy Company Obligation, there is a minimum two-year warranty for the work and a minimum 25-year guarantee for certain measures installed under the ECO⁴.

If you have not received your guarantee paperwork for works completed and lodged under government-funded or capital schemes, the order to follow is: contact the registered business first, then their Scheme Provider, then TrustMark at info@trustmark.org.uk for a copy of the guarantee information¹⁰. When claiming under any warranty or guarantee, set out the details of what the problem is¹². For the different types of protection and how they pay out, see workmanship warranties and aftercare and the HIES consumer code.

Find and Fix: no cost repairs for insulation problems

Householders with external wall insulation installed under government schemes have access to a dedicated remedial route. The TrustMark Find and Fix service offers a free home audit check of external wall measures installed under these schemes, focusing on the safety and technical standards of the work, with any necessary repair work carried out by the installer at no cost to the household²¹. TrustMark conducts these audits and will arrange for problems to be fixed at no cost to you²².

To book an audit, email the TrustMark audit team at onsitebookings@trustmark.org.uk²³. The audit is free to the householder²³. Some councils also run their own support, such as a free Home Repairs Support Service for eligible residents²¹.

For energy independence, the lesson of the complaints system is plain: registration and guarantees reduce your dependence on any single firm's willingness to return, because a Scheme Provider and TrustMark stand behind the work, but they do not remove the dependence entirely. Compensation is not part of the scheme, commercial disputes stay between you and the business, and if a firm ceases to trade the TrustMark route closes. Keep your paperwork, your guarantee documents and your correspondence, because they are what every stage of the process runs on.