Jio - Refund from Jio Postpaid not received

I migrated from Jio Post Paid to Jio Prepaid a month ago. I was told that the advance amount of Rs. ***/- that was paid while opting for a Postpaid connection, will be refunded in ** days after the termination. I received a messas asking me to update my bank account details to get refund, on *rd June which I did. Since then Its been ** days and I have not gotten my refund yet.
When customer has ended the service, the merchant needs to refund the said amount immediately.