Air India — Refund not received

Address:

Air India, 570 Lexington Avenue, 15th Floor, New York NY 10022

Air India Manager stopped my sister and mother from taking their flight from the US airport, saying my sister is sick and once she is Ok, we can call their customer care services. They will do the re-booking without additional charges, and after two months, we tried a lot of time, and they said we have vande Bharat mission under which there are limited flights. I booked a new flight for my sister and mom that cost me additional 1500 dollars.
I have been trying to make all the efforts that I could since last year, but nobody responded, and they took me round and round. I want my refund, and that's it.