This is outside of the period that either the Business/Trades Person or NAPIT are obliged to provide warranty for the work, therefore these matters are not within NAPIT remit to investigate. 

We suggest that you check the original contract to verify whether there was any extended warranty cover included (i.e. with the manufacturer or an insurance company).

Alternatively, you could speak with Citizens Advice/Trading Standards or seek legal advice to query what other options are available to you.

You may wish to contact Citizens advice, who can provide further information on your rights under consumer law and what actions you can take depending on the type of problem. 

If you're concerned that the trader might not be acting lawfully, you could report the issue to your local trading standards or Action Fraud.

You may wish to seek legal advice to help you understand your options. Some solicitors give 30 minutes' legal advice for free, and some offer a fixed fee consultation, you can contact a solicitor's firm to ask their process and seek advice.

To access further resources or to see other options which may be available to you, you can visit GOV.UK.