Versace Authentication

[twizzlet]

I found a pair of Versace flip-flops at my local thrift store.  I called Versace to ensure they are authentic; I can tell that they are well made but wanted to make sure.  The rep said the only way to authenticate them is with the imprinted code or the Versace receipt with the code.  She also informed me that flip-flops generally do not have an imprinted code.

Can I list the item as unauthenticated because of the above reasons? I don't believe they are fake but I am unable to prove they are authentic.