1. Include the
    merchantTransactionIdentifier
     (MTI) field in your original request for a PIN debit purchase
    or PIN debit credit
    . The value of the merchant transaction ID must be unique for 60 days.
  2. When you do not receive a response message for your original transaction request, reverse the original transaction:
    1. Request the PIN debit reversal services as described in Reversing a Payment or Credit.
    2. Instead of including the request ID in your request message, include the
      merchantTransactionIdentifier
       field. The MTI field links your reversal request to your original request.