I am not surprised, warranties given on ebay are only as good as your ability to enforce them.
Ebay only offers a 30 day money back guarantee and that is not a legal requirement, and it is the seller who has to refund, not ebay. Once over 30 days nothing can be done through ebay.
You don't say when you bought, but sellers can only refund through the ebay system for 90 days, so if over that time, seller did not make a refund.