Make My Trip - Discount offered but not given

The following is a copy of a mail sent to Grievance Officer of Make My Trip on **th March from mail id psarkar**@yahoo.com, to which I received no reply even after * reminders.
" I had a flight booking to be made from New York to Kolkata. I found that the ICICI Bank Offer Zone had a Make My Trip offer of Rs **** discount on any International flight ticket costing more than Rs *****. My flight ticket price made it possible for me to avail the offer.
When I first entered the Coupon Code, it said that the coupon is valid only for Mondays. I had to wait for a couple of days ( did not track whether flight ticket increased in the intervening period).
Today being a Monday, I did the needful. The coupon code was accepted and the discount was applied. When I went to make the payment, I got a message that the Coupon was valid for ICICI Bank Credit and Debit Cards only. I have an ICICI Bank Sapphiro ( American Express) and ICICI Bank Sapphiro ( Mastercard) Credit Cards - both were not accepted. Then I tried ICICI Bank Signature ( Visa) Debit Card - even that was not accepted. I got no information on what Cards are accepted. This in my opinion is a Fraud on both MMT and ICICI Bank Customers.
An early reply will be appreciated."