Air India Express — I have not received refund from last 9 months for two of my PNR

I have cancelled tickets for my mumbai to dubai round trip in Journey 1: Mumbai Intl Airport , T2, SAHAR to Dubai, Terminal
2, DXB (Return) Booked on 07/ February /2020
Outbound: Mumbai Intl Airport , T2, SAHAR Depart: 28/ April /2020
Flight no. Departing Arriving Duration
IX -247 Mumbai Intl Airport , T2,
SAHAR
Terminal T2
13:25 28/ April /2020
Dubai, Terminal 2, DXB
14:55 28/ April /2020

With pnr as - GBVWXT, CGQXQS
Its been more than 9 months and still i have not received refund as they have already deducted cancellation charges
I have been calling then from last 9months and every time they say that u will receive refund in 7days but still i have not received any refund yet