Makemytrip india Pvt Ltd - Makemytrip not returning full amount

I paid Rs **** amount to Makemytrip but they are deducting instant cashback in my refund which is wrong. They already got the full ticket ticket amount from airline but still deducting instant cashback from my refund is not making any sense at all. In case of instant cashback MMT paid the instant cashback amount to airlines on behalf of me but Airline already returned the ticket amount to them. They are not having any answer to my question & hang up the call stating that we will get back to you and then closed my request