Air India — Refund

I had booked two tickets from Bengaluru to Chicago & back for travel on 20 Jul 21.
PNR HP61B, Ticket Nos[protected],[protected]
Due to travel ban by USA those days, I had to cancel our tickets. I was told by call Centre executive that "since USA has banned incoming travelers no cancellation charges will be deducted".
I had paid Rs 1, 49, 078 for the tickets. Air India levied cancellation charges, which is unjustified at the prevailing circumstances.
I was refunded Rs 1, 20, 878 after deducting Rs 28, 200
Kindly refund Rs 28200.
We are frequent flyer with Air India Nos[protected] &[protected]
We are again travelling with Air India PNR YYH7R