Spice Jet Airlines — Not refunding amount for cancelled ticket

I have booked ticket for my Mother under PNR#PJ7BE for an amount of around INR 15000 which I have to cancel it due to some reasons. As per policy they have deducted cancellation charges of around INR 6000 and balance INR 9000 they have kept under my mother name to be used for future ticket. Now My mother surname got changed and when I am trying to utilize balance amount, system not allowing to use. So I approached customer care of Spice Jet and shared all details for which they asked me to send a mail to Spice Jet customer relations mail which I did on same day mentioning my Bank Account details to refund the amount in my Bank Account but till date I have not received any response from team despite of sending reminders every day since 20 days. Also approached Spice Jet through Social Media but no response.

Please help to get my balance amount in my account from Spice jet