The seller has it backwards. She should go to the Resolution Centre and start the Mutual Cancellation request. You then agree (or ignore, which just slows things down.) and both of you are released from the transaction.
Now just a little advice. The time to check if the seller will ship to Canada and how much it will cost is BEFORE bidding. There is a Shipping and Handling tab right beside the Description tab, which will give you this cost.
Be careful, many US sellers have been roped into the Global Shipping Program, which offers them certain protections, but which improperly used costs the buyer a small fortune in otherwise uncollected duty, tax and fees.
If the listing has these words:
Customs services and international tracking provided
Read carefully because that is where you may get caught by the GSP.
