Hi, THank you for your question and welcome to Just Answer. Have you provided an invoice for the full amount owed? Did the customer agree to the quote in the first instance?
Kind regards AJ
The customer has received an invoice in full and agreed to the original quotation.
Hi, Thank you. This is simply a case of breach of contract. The customer contracted you to do work, you completed the work and now they wont pay. It is a debt recovery matter and can be dealt with in the small claims court.https://www.moneyclaim.gov.uk/web/mcol/welcome you can start a money claim. In order to defend this claim they will have to give you a defence as to why they wont pay, this will include disclosing the faults. In any event there is no right of set off, if there are faults they have to give you an opportunity to fix them. If the faults led to damage then they will have to prove the damage and you may have to pay for the damage. What I would note is none of this is grounds to with hold payment for invoiced work that was agreed. There only defence would be they dispute the invoice, and the onyl way they could do this is if they could prove they never agreed to the quote in the first place.
I would suggest you start by sending them a 7 day letter before action. Demand payment of the invoice in full within 7 days otherwise you should issue a claim in the county court.
Do your terms and conditions allow you the right to charge interest? Kind regards AJ