US Code
Part D— Credit Billing
§ 1666e. Notification of credit card issuer by seller of return of goods, etc., by obligor; credit for account of obligor

With respect to any sales transaction where a credit card has been used to obtain credit, where the seller is a person other than the card issuer, and where the seller accepts or allows a return of the goods or forgiveness of a debit for services which were the subject of such sale, the seller shall promptly transmit to the credit card issuer, a credit statement with respect thereto and the credit card issuer shall credit the account of the obligor for the amount of the transaction.

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