A problem like that is going to be hard for anyone on here to help you with. My advice would be: 1. Get a good body shop to mess with it so it fits right. Might cost you some extra dough but you probably want your Z to look nice I'm guessing. 2. Send it back and get a new one if you think you just got a bad one 3. Live with it on a little crooked. 4. Don't put it on(my favorite).
Body work is a little different when talking about problems with it. It's different when we're telling you how to put in a ProfecB...which we can walk you though. This might not make sense but i tried at least you bastards.