You can complain through the ebay reporting process/resolution center, but not sure what will come of it:
- As stated in the User Agreement, ebay can't force a seller to sell, nor a bidder/buyer to pay.
- Unless the seller sends you a "Request to cancel" and you click "I agree", the seller will still have to pay ebay the appropriate Final Value Fees associated with the "successful sale".
- As the buyer, you're allowed to leave appropriate feedback for this seller not completing the transaction (as you've done). Sellers are not allowed to leave appropriate feedback for bidders/buyers who do not complete a transaction.