Indigo Airlines — Refund ticket amount as flight cancelled reg

Address:

Hyderabad, Telangana, India

Dear sir,
I have booked air tickets (For my brother and my son) from chennai to hyderabad in indigo airlines. Day before i got message as the flight was cancelled. Hence, i am asking to indigo to refund my ticket amount rs 8800/- as the flight was cancelled by indigo airlines.
But, till now indigo not refund my amount, instead of they are telling to use credit shell.
As per credit shell other persons couldn't use to book. Hence i couldn't use credit shell as my brother and my son are in different states.
I am not interested to use credit shell. But indigo not accepting and not refund my amount.
Pnr no: fkn8vg
Destination: chennai, tamilnadu, india
Date of travel: 02.06.2020
Name: sivakumar
Mail id: chakrapani. [protected]@gmail.com
Kindly help me for refund my amount.
Regards,
S. Chakkarapani
91-[protected]