Have you asked him about that?
We sellers are required to ship to the address the buyer supplies. Which is why if you move house, one of the many tasks is changing your postal address with eBay and why sellers usually refuse to ship to any other address.
EBay only recognizes a few authenticators and expertisers, so if the item did not already have a good certificate from one of those, it would be meaningless to eBay if you decided to return it as Not As Described (ie not authentic).
At this point you want the seller to give you the tracking number, the service used and the window for delivery. If he can't or won't supply those (the tracking number is the only important one) you can open an Item Not Received dispute on eBay or more easily on Paypal.
The eBay Resolution Centre is at the bottom of this page.
The PP Resolution Centre is at the top of your account page under Tools.
You are also protected by the chargeback policy of your credit card, if you used that to pay for the item, with or without PP.
But start with the seller.
Transactions are rarely shut down, and usually for important reasons, like selling counterfeits.
