Once youve given them the flooring you are not in ownership anymore, you have handed ownership to the customer, they now owe you for the flooring, so if you start ripping up, by law it's stealing. There's some crafty people out there who know how to play the game.
Have u got a contract ? Or any corresponce from them that u got the job? As I deal with Thomas Higgins Solictors they are really good. They charge like £3 for a letter. And I have got my money back just from that letter. They only deal with business to business debt
Send a notice before action threatening a ccj, that should help push it along but be prepared to follow through with it, you can do it all online nowadays on the mcol site
The most important questions are; why are they not paying, and, if anything, what are they claiming? They may sound like the same question, but the're not. Although the answer may be the same to both. They may not be paying because they are simply scum and think it's acceptable behavior and that they can get away with it, or they may genuinely believe they have a case for withholding payment. Once we understand that we may be better able to advise. Good luck by the way. It makes my blood boil when people take the piss!!
Try sending the letter as a first course of action, take the professional approach first. If that gets you nowhere then......... improvise