This is why if at all possible I always stand and watch the person doing things on my car, and shout if they don't do it right. Okay, it's inconvenient for me but I'd rather have that than getting my car bolloxed. Some of these places don't like you being in the bays, but I'd rather take it to somewhere else than chance this sort of thing happening.

Nightmare for you mate, I hope you get satisfaction whichever way you decide to go.