Irctc — cancelled e-ticket amound not yet not refunded

I have booked a ticket to new delhi from bettiah on 25 apr 2018. Due to train delays i have cancelled the ticket on 26 apr 2018. The ticket has been cancelled successfully, and in the cancelled ticket option it is showing (Still) "sent for refund" but amount still not refunded back to the account. I have contacted to the irctc customer care many times, but could not get any reply.

What should i do to get the money back?

Kindly help me the needful things.

Ticket details,

Pnr number : [protected]
Date of booking : 25-apr 2018
Total ticket fare : rs 4390.00
Cancelled date : 26-apr-2018
Refund amount : rs 2190
Refund reference:- 74332748120811922283927