Just to add, I take it you're aware that eBay won't get involved in warranties and doesn't provide any buyer protection for cars anyway.
I can't believe that you bought a car on eBay without even getting the seller's details. Surely they gave you some sort of receipt for the transaction?
The bad news is that warranties offered on eBay are only as good as the seller who offers them. All too often sellers don't want to know. Any meaningful warranty will make clear who issued it, and how to contact them. If yours was not in writing and doesn't give this information it's not a good sign. Good luck anyway!
