It's rare, but occasionally a merchant fails to use the buyer's prepaid label. If that happens and you get billed for shipping, you should request reimbursement from the buyer. This is easy to do and the buyer has already agreed to reimburse you. You can Request Reimbursement using the button on the right side of the order details page. Write a short note to the buyer and enter the amount they owe you. Once the buyer pays, those funds will be deposited directly into your bank account.