Don't post in ALL CAPITALS. It is considered to be shouting, and very rude. Also hard to read.
This is a member to member Board, and neither your seller nor eBay employees are likely to see your complaint here.
First contact the seller. There is a link for this somewhere on the listing. (I swear the links move around when you blink. Worse than Weeping Angels.)
If the seller cannot clear up the problem, ask for a Mutual Cancellation. This will free both of you from the transaction when you agree to it. Both of you can leave feedback.
But be very polite, because if the seller fears negative feedback from you he may instead open an Unpaid Item Dispute. If you still refuse to pay, you will get a Strike and will find it harder to bid on eBay in future.
Now. About the 'too many things."
Did you see a Free Shipping icon on the listing?
Sometimes those show up when only domestic shipping within the USA is meant. Always double check what shipping will be to Canada. Some of those sellers do not even ship to Canada,which can get very messy and unhappy.
Did the full listing (not the one on a mobile device) show this statement:
Customs services and international tracking provided
If so, the US or UK seller is shipping with the Global Shipping Program and you will be required to pay applicable Canadian duty and tax, plus a service fee, before the seller will ship.
Is the Canadian seller charging GST/HST/PST?
While most sellers are small home-based operations, some are large enough to be required to remit sales taxes as applicable. The seller's GST number would be on the invoice.
Take your time and think about what those charges are. There are some charges that cannot be added.
Sellers cannot charge for insurance. That is included in the shipping charge.
Sellers cannot increase the advertised shipping charge, even if they goofed and advertised a cost below what it really will cost them.
If the seller is in China, btw, there is a very good chance that you will never get your 'custom made wedding gown' or that it will be badly made and not to your supplied measurements. In that situation, I'd accept the Strike and move on.