Hi
-first file a claim to ebay in buying/selling 
section. Try to keep all documents about 
transaction ( item page, way of payement, 
emails,etc...) Don't hesite to complete the 
claim! I had, and now I'm really embarrassed!
-let neutral feedback to this seller to prevent 
other people.
-write to fraud.org to tell them your problem. 
They can help you too. Give them email and 
coordonnées from your seller.
-try to write to square trade via ebay site. It's 
a resolution dispute system and it's free! 

Perhaps the seller 'll have a reaction when he 
saw you tries several ways to have your item.

-if you have paid via credit card or paypal, 
contact your credit card service. It's fraud and 
they can help you to refund back your money if 
ebay doesn't.

I've actually in the same bad situation..., and 
that's what I have done. I Hope you can have 
refund better than me! Good luck