Air India — Ticket not refunded

I have booked my air india flight ticket for the travel from Frankfurt to Chennai for the date 07.10.2020. Air india cancelled all the flights between Germany and India upto oct 16, 2020. Since I went to India for an emergency case, I didn't want to reschedule my flight for the future dates. So I took another. Its been almost a year and I haven't got any refund from Air India. Whenever I talk to the customer care they tell to fill the complaint form and they will get back in two days and I have not got any update from them. Now they are telling the refund is done and I have not got it in my bank account. I tried mailing them with account statement and now again they don't reply. This is very hard and stressful.