What would you do ?

FluffyKitten69

We fitted carpet for a customer. Our fitter (sub-contracted) has over 20 years experience and we've never had a complaint before. 
He fitted carpet onto some stairs. The underlay was stapled to the stairs and carpet fitted on top. The customer complained that there were "dimples" from where the carpet fell into the void left by the staple pulling the underlay down. We couldn't see it, but the carpet was taken up and tape put over the staples. This seemed to sort out the problem. She is refusing to pay saying what will we do if the marks come back in 10 years time (yes, 10 years) any suggestions for a letter example would be greatly appreciated. 

marcia_

Letter before action then court 
https://www.citizensadvice.org.uk/law-and-courts/legal-system/small-claims/Problems-with-goods---letter-before-court-action/

gwynlas

She complained you responded and you know that the carpet fitter is sound, problem apparently solved.

She owes you money which you can enforce collection on end of story.

She might try and leave you a bad review but hopefully you would have right of reply and be able to state story above