Air India — Never Received Refund

I booked a flight for my mother in March 2022, which I had to cancel for some reasons. As per the policy, I canceled this flight a month ago before the due date. I have called Air India many times. Every time customer service agent tells me that they have submitted the request. 5 months have been passed. I still have not received airline ticket refund. I had very bad experience with this company.