Air India — No refund issue though cancelled ticket from past 1 year.

I have purchased Air India economy class 4 tickets of round trip from New Delhi to Patna with dep date 29 April 2021 from New Delhi to Patna and arrival date 2May 2021 from Patna to New Delhi. I cancelled the ticket with the time frame allowing to cancel the ticket over telephonic conversation and was assured that refund will reflect within 20-24 days but I didn't got any .Upon complain they said to mail the ticket and transaction Id but no measures were taken to return the amount. All they did was to not take request seriously and neglecting the same for over an year till date.