DGCA — Vistara fraud in air ticket refund - WMX9WT

I had a 2 way ticket with vistara from London to Hyderabad and back from Hyderbad to London which I have bought for approximately 57, 000 INR. I had flown from London to HYD on 11th dec without any issues but my return flight which was scheduled to be on Jan 4th 2021 was rescheduled many a times and got cancelled in the last minute so I have asked for a refund and the operator/customer care person confirmed I would be getting 25, 000 INR as my refund even though my ticket was around 29, 000 INR including flexi charges to which I agreed, but finally I am not sure why operator has refunded just 6, 520 INR.
They promised me to initiate a full refund as my ticket was flexi ticket and also flights has been cancelled by airlines itself and 6, 520 INR is no where near my booked price. Airlines are doing fraud with the refunds and I would request you to please look into this issue.

PNR : WMX9WT
Phone # +91-[protected]

Below is the Cost break up for my ticket for reference and if 6, 520 INR is the refund amount I would like to see the calculation based on which they have provided me the refund.

Adult Passenger(s)
Charges to the airlines
Base Fare INR 43, 845
India: User Development Fee INR 464
Total charges to airline INR 44, 309

Taxes & Fees
Surcharge INR 320
Surcharge INR 200
Aviation Security Fee (P2) INR 451
Tax description unavailable (GB) INR 7, 608
Tax description unavailable (UB) INR 4, 628
Total taxes, fees and charges INR 13, 207
INR 57, 516
x 1 Adult(s) = INR 57, 516
Total price for all travellers = INR 57, 516