what would be the best action to do?
As you're aware that it's too late for eBay to do anything, it would have helped to tell us how you paid. Your rights depend upon this (and possibly also on what you paid for the bar).
If you paid by credit or debit card your best hope is to contact your card issuer. Either could potentially issue a chargeback, but if you paid by credit card and the item cost over £100 you may also be protected by section 75 of the consumer credit act.
Without knowing the cost, it's difficult to suggest any legal course of action, although anyone selling fake gold bars has probably put themselves well beyond the reach of the courts anyway.
Doesn't anybody read eBay's warning that they don't guarantee that sellers' descriptions will be truthful, or that items will be safe, legal - or even exist. Would you have bought a gold bar from a shop that stated this??
