Answer:
How the customer used the card would potentially make a big difference! If the card is used with its PIN, the transaction doesn't run through the MasterCard or Visa network, so the card association chargeback rules and procedures would not be available. That would leave Reg E, which provides no relief at all. Assuming that the customer used the card in "signature" mode or over the internet or telephone, the Visa or MasterCard chargeback rules, if applied by your bank, might provide your customer a refund.
First published on BankersOnline.com 1/07/08