If you are importing anything into Canada by mail over $20 CAD in value, it is reasonable to expect to pay import fees (taxes, tariffs and a handling fee) when or shortly after it arrives. If it is mailed via Canada Post, it will be collected at the door by your letter carrier, or when you pick it up at the post office. If it comes via courier, you will ether pay at the door or be invoiced later, depending on who it is that has brought it.
Sometimes the parcels come through without additional taxes even when they could have been assessed. It is a gamble. And handling fees vary widely between Canada Post and the couriers.
Whatever happens, don't blame your seller. It's the responsibility of the buyer to be prepared for this possibility.
If you have to return your car part, use tracking, and then apply to have your import fees refunded.
Best of luck.
