The only shoes showing as sold on your account were sent to the buyer through the authenticity centre.
If the buyer wants to return the shoes, they need to open a case through Ebay.
Then they have to send them to the authenticators.
If the shoes are not in the same condition as when you sent them, the case will close in your favour, the shoes will be sent back to the buyer, and they will not get a refund.
Tell them, if they want to return them, they need to open a case through Ebay.
"There are two ways to be fooled. One is to believe what isn't true; the other is to refuse to believe what is true.”
Søren Kierkegaard, Danish philosopher (1813 - 1855)