Is the seller in North America or in overseas?
Some sellers are “dropshippers”. They list from a catalogue and when you buy the item is shipped from the warehouse somewhere else.
If this is the case with your item, you return it to the SELLER, not to the shipper/warehouse. This can be a great saving since shipping overseas with Delivery Confirmation starts around $40 (ExpressPost International is the Canada Post service you would use.)
One of the reasons experienced buyers are cautious about buying from overseas, especially high fraud items like electronics and tricky items like clothing, is the very high cost of return for refund.
Even if the seller refuses to refund, Paypal will refund you and go after him for their money. But talk to him first and keep everything as friendly as possible.