Mastercard Reason Code 4860

The merchant agreed to a refund, but the cardholder says it was never actually issued.

A promised refund wasn't processed, was processed late, or went to the wrong payment method.

If the refund truly wasn't issued, process it immediately rather than contesting; otherwise prove when it was.

Refund transaction record with date and amount, or support correspondence showing no refund was promised.

Approving a refund in support chat without immediately processing it in the payment system.