We submitted a chargeback (using the reason Merchandise or Service Not Received) for a customer who used her Mastercard debit card to purchase some items from a seller through a Facebook group. Our customer states she never received the items she order but was charged for them.

Today we received a representment notice for the transaction. The merchant sent us a copy of the invoice and a document labeled "Payment, Merchant & Buyer Details" which shows the same information as the invoice with the following summary: "The cardholder authorized this payment by entering their card details through a secure online invoice system. CHs authorization of payment serves as acceptance that goods/svcs were satisfactory. Please see attached payment documentation."

This "proof" does not seem to actually prove anything, other than the fact that our customer authorized the charge, which is not what she is disputing. Since this is not a Reg E claim, what do we do now?

Under Mastercard rules, the next step would be to obtain an updated letter from the cardholder stating that the merchandise was not received and noting that nothing in the representment documents demonstrate that merchandise was received. You can then file a pre-arbitration claim against the merchant.