GoAir — goair cancel flight - not picking up call - did not refund money

Go air canceled a flight on 21 dec 2019 at 6am from goa to mumbai. They sent me a message at 2am notifying about the cancellation.

I've been trying to email and call go air, but am not getting any response. I've attached tickets below, and a stamp i got from the front desk of go air approving the refund for the ticket. The details of the flight and the amount are also mentioned in the attached image