If the company doesn't want to do anything, or if you can't irrefutably prove fraud, not much you can do except a civil suit. This would be very costly, probably more than you spent on the motor. Best thing to do is find a reputable local company and have them check out the motor and see if the machining is done properly. Other than that, live and learn is pretty good advice. I will only use a machinist that I know and trust.