Vistara — Unable to redeem amount from canceled flight

I had booked a flight on the 1st of June 2020 from Delhi to Kolkata using MakeMyTrip but the flight got canceled Due to Operational Reasons from Vistara's end. I contacted Vistara on the 5th of June, 2020 about this, where it was said that the amount would remain in my wallet, that I could contact Vistara to book another flight within 31st of March 2021 using this ticket's amount and that I would need to only bear the extra charges if applicable (call recording attached). I was not asked to create a Club Vistara account at the time and to just keep my Ticket Number and PNR number ready.
Today I contacted Vistara to book a ticket using the amount which should be available but it was said that I cannot use it because I have no Club Vistara ID. I have provided all the necessary information but I am not allowed to use the amount from the canceled flight. Please allow me to book a new ticket using the amount from the canceled flight. I am ready to create a Club Vistara account if needed.

Details of the canceled flight are below:
1. PNR: Q3OQFV
2. Ticket Number:[protected]
3. Passenger Name: Kaekasha Dutt
4. Flight Number: UK-707