Spice Jet Airlines — credit shell validity

Address:

India

I booked a flight ticket for my family with spicejet, the travel date is supposed to be in july 5 but due to covid situation the flight is cancelled by spicejet and informed us that the flight is cancelled and the amount is saved with them as credit shell and we must travel within march 31, 2021.

I approached the customer service and requested them to either refund or extend the validity up to one year from the proposed date of travel, but they are denying both. I further escalated the issue to nodal officer of the same company, the response is same.
My pnr number is zi1jjh.