That means you totally depend on the seller's goodwill. If it's not too late, don't use negative words (like fraud or police), just return the medals and say they are not as expected, please return my money. If the seller doesn't, you are left empty-handed, but that's in fact what you are now.
Ebay facilitates the life of thieves and fraudsters. I boycott them and that is the only way never to be frustrated by their immoral behaviour.
Peter