Cheapticket.in / Airtickets India — no refund post cancellation

I had booked tickets and gotten them cancelled. I was supposed to get a refund of 12, 000. I have been calling their call centre for over two years with no refund. They instead put my call on hold after asking the booking details. I have waited for more than 2 hours on hold. Following are the booking details

Booking id: 3672179.
Pnr: fkweqr. Bom 2018-may-17 12:10 - vns 2018-may-17 14:20. No. Of pax: 3. Status: confirmed.