[Kjesse]

That's a pretty crappy way to treat a customer since they made the original mistake. Your only mistake is not catching it right away.

They're liable to install the proper part, because you contracted with them for the proper part. They are supposed to be competently able to identify and install the proper part. The fact that you used the wheel does not matter, because it is the wrong wheel. You missed noticing a defect which, while obvious, is easy to do. You asked for the replacement part and in your head assumed that is what they did, at least partially because they told you that is what they did. You did not have reason to carefully inspect and compare the new wheel to the other wheels. They on the other hand should have compared with part numbers. You don't have access to their catalog, and might not have known that the style of wheel comes with either 6 or 4 spokes, while they must have.

I'd want to see the exact wording of the document you signed approving the repair, although even if it says "I confirm the work and parts were proper and installed correctly", that does not end the matter. Both they and you thought it was the proper part, there was a mutual mistake.

Escalate it to the manager's level. If management does nothing, its not exactly something you sue for in small claims court, not enough money is at stake. Get them back by posting the dealership's name and story on beyond.ca. As long as you post the truth, there is no defamation. And of course, vote with your own pocketbook when it comes time for another vehicle purchase.

Edit: Also agree with Pinner's second comment, checking the part numbers might shed some light on the situation.