File an "Item Not As Described" dispute.
You will still be required to return the item to the seller, with Confirmation of Delivery and Signature Confirmation if the value is over $250, but you will be refunded the entire original payment when you can show eBay that the watch has been delivered. (NOT shipped, delivered.)
When you return the item, mark it as Returned Merchandise. On the back of your original receipt for the shipping and duty and tax, you should find the phone # for CBSA. If not they have a website.
You can be refunded the tax and duty on returned merchandise. You will not be refunded the service/brokerage fee.
You have up to 60 days to leave feedback. This is a useful tool, Don't leave feedback until you have your money back. The most effective FB is calm and factual.
When you leave FB you will also be asked to leave Detailed Seller Ratings of your experience. The normal Rating is Five. The lowest is ONE. No stars is a free pass.