I received a bad part. What should I do?

To much of this crap going on, if you can't take a guys word for it then where the hell you suppossed to stand. He gets the money you get screwed. Gotta start finding a way to protect the buyer. money's to damn hard to make just to throw it away on some a*@1holes word. I just recently got screwed on a sour 340 in a 68 gts. Not only did it have a spun bearing but all the so called trick parts and machine work didn't exist either. Seems like these guys are just getting away with it.:banghead: