If something goes wrong with an account you delivered, you can propose a replacement in the affected order. It is a proposal, and the buyer is free to turn it down. Whether it settles the order is decided by support under the policy covering that order.
Reply inside the affected order, so the proposal stays attached to the sale it relates to.
Describe the replacement accurately, including every way it differs from what the buyer originally paid for.
Send whatever listing details or evidence support asks you for.
Wait for support to confirm the proposal can be used.
Deliver the agreed replacement through the order once you have that confirmation.
Do not lean on the buyer to accept it, to close the case, to change their feedback, or to give up any other review still open to them. Do not tell a buyer that a replacement will head off a refund, a balance adjustment, or any other outcome, because it does not work that way. Support weighs what happened against the policy that applies before deciding whether your proposal resolves the order, and that decision sits with support and the governing terms rather than with either side of the sale.
A refund is still possible after you have offered a replacement, in the cases where the order could not be delivered as promised. Can I get a refund? sets out which those are.