GoAir — refund not generated by the airlines

Address:

Mumbai, Maharashtra

My client had booked a flight from kolkata (Ccu) to bagdogra (Ixb) with goair, the principal agent being m/s kafila holidays. The flight no. Was g8-538 with pnr byypgq and the travel date being 03/06/2020.
The booking was made under corporate booking as per the airlines' terms which allows full refund upon booking cancellations.
I tried to communicate with the airlines on their customer care numbers but the calls remained unanswered even after holding the call for 30-45 minutes.
Again i tried to communicate via email and got a reply which is attached herewith. The terms laid out for re-booking are stringent by nature, moreover they are not operating any flights in the near future for the said sectors as per their terms.
I kindly request you to help my client get the full refund of the booking amount as there are not many options left.