Makemytrip - Didn't pay me back my full cancellation refund from air india against their own T C

I had booked to and fro tickets for * passengers from Kolkata to Singapore. I then cancelled one of the passengers from return flight(Singapore to Kolkatta) by calling the airlines. The airlines confirmed that as per policy **** rupees will be deducted and then will pay back ****.** rupees to my airline. As per T&C of makemytrip(pls see screenshot), they are only supposed to charge *** rupees extra. But, as I had used a cashback code of **** rupees (on complete ticket amount, close to *lkhs), they deducted **** rupees from the cancellation amount of ****.** rupees and just paid me **** rupees .
As per their partial cancellation policy, it should be pro-rated(please see screenshots). They are not paying my money back.

To be fair to me, they shouldnt charge more than *** rupees from me but they are charging **** rupees when I just cancelled * ticket(around **% of total booking amount of *lks). This is unfair to me as a customer. Please help to get my money back.