regardless of what carb was in the box or how he ordered it he should be able to return it without a hassle. my families business ships parts all over the world and we accept returns without giving people a hard time, if its our mistake that they received the wrong part we pay return shipping but if there returning it just because they changed there mind or they ordered the wrong part then they are responsible for the shipping. that said if the customer calls with a problem and cant act like an adult and speak to us with respect and understand that mistakes happen then we might make the return process as much of a hassle as we can.