Since the customer authorized the original charge, and the correct amount came out of their account, Reg E does not apply to this situation.
However, VISA/MasterCard rules do have options available for you to be able to help your customer. The chargeback time frame for this situation is 120 days after the latest promised delivery date of the merchandise not to exceed to 540 days after the date of the transaction.
What this means is that you can go back 3 months to file a chargeback on the disputed charge. File MasterCard chargeback code 4855 "Goods or services not provided" or VISA chargeback code 30 Member message 2 "Merchandise not received." In order to refute the chargeback, the merchant must provide proof that they have provided the merchandise to the customer. If they cannot, they lose the dispute and you will have recovered the funds for your customer.
Also note that although Reg E does not apply, VISA/MasterCard require that you provisionally credit your customer's account once you file a chargeback.
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