Air India — No refund since one year

We had booked return tickets (US- India) with Air India last year for $1733. We utilized one leg of the ticket (US to India). However, we did not utilize the leg from India to US since US has imposed ban of entry of Indian citizens in May 2021. So we had to cancel the ticket as we could not travel. Ever since we are awaiting refund from Air India for our one unutlized leg of the itinerary. Air India processed a refund of $96 last year with no explanation as to how the $96 was calculated. Ever since we are awaiting details from Air India but no response. I am attaching all documents and communication.
PNR: JKK4K