Why have you not availed yourself of eBay's Buyer Protection program?

eBay will broker the transaction and ensure that you are refunded the full original shipping, provided you follow their rules - including returning the item to the seller and providing tracking information. You are not entitled to additional shipping.

Do not delay in responding to the current case. If you refuse to respond, the decision will default to the seller, and the refund to you will be reversed. There is a box for you to tell your side of the story. Do so, and escalate the case immediately to eBay's customer service department (there's a button at the bottom of the current case for this option).