Hi
@mjacksonplastering
You need to take an invoice round and hand it to the guy personally (also email one) giving him 24 hours to pay.
If he refuses to pay ask him to email with what reasons he is withholding payment. If his reason is only sunlight and artificial light then you have him by the balls.
You cannot judge Render under artificial light or glancing sunlight. You just can’t. There’s a few articles on the web that would be handy in court if you needed.
If he doesn’t pay within the timeframe you’ve allowed, issue a letter before action and allow another 14 days or so.
Then go to MCOL at gov and start the process of taking him to the small claims court.
You cannot allow customers to treat you like this. You should have had a contract (hopefully you did) to Render his house in whatever finish agreed. You’ve done it, so he should now pay.