Airtel — For unutilized service they charged me extra

Since airtel digital tv is not having the feature of holding the account in safe custody for long time they are saying the call is not made from my side and they are hesitant to give my money back. I have not used my account from 7th june 2020 to 11th Apr 2021. But for that rent has been charged. I have written enough mails to customer service but that of no use. 100 mails had been written and 28 reminders have been sent. I am having call recording for that customer service call. They are not answering that too. Have attached the last mail communication too.