Have him take it off for free, and refund your money so you can get it put on by someone else who knows what they are doing.
what he said. the guy might not be good at installing bodykits, and trust me, if he made mistakes several times, hell do it again. goto another good body shop, get an estimate of what you want that the other guy ruined. goto the guy who fucked you up, and show the estimate and ask him for the price. if he offers you to fix it for free, dont accept it unless hell do something extra for free. if he disagrees, hit the court. im pretty sure he wouldnt wanna get into that big of a mess. if he goes, and probably loses, hell get a huge penalty! a penalty is to shut down the shop for a week, maybe longer. if he doesnt, then they will close the place. penalty stays in the record for 3-6 years. and when the shop is penaltied and a week shut down, the state puts a note infront of the shop saying they broke a law. embarassing! so mainly if he doesnt accept ur offer, threaten him by suing him!