Did they pay> If not wait 4 full days then go to the item in your Sold section More actions Buyer has not paid. You get your fees back and the non payer gets a non payment strike on their account.
If they have paid just wait and see what happens.
Once it is sorted out then put them on your blocked bidders list so they can not buy from you again
https://www.ebay.co.uk/help/selling/resolving-buyer-issues/blocking-buyer-ebay?id=4082
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