Always two sides to a story ...
I am sure there is, but you have to admit some people will try and con you at every opportunity, I've met a few that are unbelievable, and certainly wouldn't want to be involved in 15k transactions with them.
Although he obviously lossed his temper with the situation, I don't think it would be in any way unfair, is he removed the entire extension, returning it to its previous condition and refunding them any partial payments they made. The last thing I would want to see is people getting away with refusing to pay.
I have heard a few window cleaners being owed a fortune from large jobs and getting shafted.