MakeMyTrip India — MakeMyTrip - Flight Cancellation Payment Not Refunded Fully

I have booked a flight from Chennai to Bhubneswar on 21st May using MakemyTrip app Booking ID - NF[protected], but due to lockdown the flights were cancelled by the Airlines itself and the airline Indigo has refunded the entire money.

I have called up Make my Trip customer care, and they have told that they will refund all the amount. Later when I checked in app, I noticed that they have reduced Rs 290 as convenience fee.
When the flight was cancelled by Airlines and also refunded all the amount deducted. Why Make my trip still deduct amount from it and refund the rest ?

Also, called customer care for asking reason, but he was not able to justify it.

I need to get the refund for the amount as the cancellation was not from my end.

Thanks & regards,
Satya