Vistara Airlines — refund not credited after flight cancellation

Website:

www.airvistara.com

I booked tickets on vistara airlines flying from delhi to guwahati on 17april 2020. I booked the tickets because they opened the bookings after the lockdown period. But my flight was cancelled by the airline due to their operational issues and when i contact them they asked me to reschedule my flight along but the charges will be applicable while rescheduling. I am feeling cheated. They were the one to cancel their flight then why should a poor customer pay their inconvenience. My prime concern while booking was the fare of the ticket now that i need to reschedule it, it will cost double. The thing is why should a customer suffer their inconvenience. I asked them to adjust my pnr for the next flight flying to my destination but no response was made. This is totally injustice. I request you to ask them to refund my amount or provide the services in the same rate which i opted according to my budget.