The seller took the account back
Before completion, a reclaimed account is an ordinary dispute. After completion, a proven reclamation permanently suspends the seller.
Before the order completes, reclamation is covered like any other seller problem: open a dispute on the order.
If staff establish that the seller reclaimed a sold account after completion, the seller is permanently suspended. AuctionHouse does not issue a commercial refund for that claim, including when the seller has already withdrawn. A report or loss of access alone does not establish reclamation.
Your statutory rights and bank or payment-provider remedies are not affected.