IRCTC
Non refund of e TDR after almost 2 years

I booked a e-ticket from Patna to Mumbai on 11/4 train no. 142P in IIIrd AC for Rs. 1253.00. The PNR no. was 6226517253. On the date of journey the train was late by 20 hrs. I made my travel to Mumbai by flight. I filed TDR on 18/5. Even after no. of reminders and talking on phone the refund has not been made so far. Non refund after almost 2 years is pretty long time.

Can anyone suggest what to do?