Airtel — Complaint regarding non-refund of balance amount of airtel broadband connection DSL ID[protected]

I(Dr. Reeta Rani Jha) had taken my Airtel no [protected] with broadband connection having DSL ID[protected]_dsl and plan Airtel-UL-Xstream Basic 799 Unlimited GB
(100Mbps/1024Kbps) COMBO Plan on 29 Sep 2020 for three months. For this, I paid Rs2828 (bill attached) and also got free modem for taking a three-month subscription. This expired on December 30 2020, and I again took a three-month subscription by paying
Rs 2828 on January 4.

Post this I shifted to another place on 7th Feb 2021, and consequently applied for the transfer of my Airtel broadband connection, but due to feasibility issues I could not get the connection transferred to my new address. I then applied for discontinuation of the service on 10th of February 2021, and received a confirmation from Airtel customer care that my Airtel broadband connection has been deactivated, and I would get refund for my extra payment of 47 days within 45 days at most.
All of this I had mailed to Airtel customer care email address [protected]@airtel.com and they gave me a reference number[protected] for the complaint and assured that they will resolve the issue before 3rd of April 6 PM. They asked for these documents: -
1) Bank Cheque
2) Bank Account Number and other bank details
in order to refund my money.I responded the mail with all required document but the matter is still unresolved and I never received a refund even after their final deadline of[protected], 6 pm.