Babylon,
I am pretty sure under consumer law, you must give the panel beater the opportunity to make goo dht erepairs that you are not satisfied with. It sounds like you have done this 3x. Now there is one of 2 things happening here: Either you are too picky and cannot be satisfied or The job done is crap and they cannot get it right.
I would suggest that you get a 2nd and 3rd opinion on the work done, get it in writing from another panel beater. Armed with this info, go back to the origional place and ask them what they want to do about it. If they do not give you a satifactory response, pay to get it fixed by another place. Then you can sue the panel beater who messed up the work.
The Dpt. of Fair Trading should give you similar advice. You can also contact the Motor Trade Association (MTA) and make a formal complaint about the workshop.
Do not give up, if you paid you hard earned for a propper job and did not get it, do not just rollover and accept it. Kick some butt :kick: