Indigo Airlines - Refund not given

I am Arun Balaji N from Tirunelveli, Tamilnadu. I had booked air tickets for * passengers with Indigo Airlines. The air tickets were booked on February **.
The traveling date was May * for the journey from Chennai International Airport to Mumbai International Airport. This ticket was booked under PNR number JGM**P.
And the return journey was on May * from Shirdi Airport to Chennai International Airport. This ticket was booked under PNR number BIBJUZ. The price details are as follows:
PNR JGM**P: Rs *****
PNR BIBJUZ: Rs *****.
A total of Rs ***** was spent for these air tickets. Owing to this current COVID-** pandemic situation, the airline canceled all the services for the above mentioned dates. The situation is understandable. But, since the airline had itself canceled all its services, it is fair only when it refunds the money that has been paid.
When I contacted the airline about refund, one of the officials who I spoke with had told me about Credit Shell. He told me that they will park these funds in the form of Credit Shell, where I could use that fund to book air tickets within the next one year.
Out of the * passengers about * passengers are above ** years of age and with almost no clarity on when this pandemic situation might mitigate, it is very difficult to even think about this journey in the current future. Also, the government has asked to refund the money for passengers whose travel dates fall on the lockdown dates. But the airline said that they had not received any such instructions. Approximately Rs ***** is stuck with them with us not traveling at all.This is hard earned money and with travel not undertaken it is their responsibility to refund our money back to our account. It has been about five months now and I do not have any clarity regarding this issue.
I had also booked railway tickets in the same time period and since the services were canceled, they refunded the money. But why can't the airline company refund the money to me? Rs ***** is not a small amount and please help me to get a refund to my account. I hope that I will receive justice since this is a genuine request and I firmly believe that your response will bring me hope that I will receive a refund from the airline company.