Hathway — Repeated calls and account termination

My hathway account number:[protected]
Last year (January 2020), we stopped using the hathway broadband connection. We keep on calling the customer care for termination of our account and asked them to come and take the modem. But they kept calling me for renewal. Everytime I called them, I told them to terminate the account and they didn't do it. In the August month they charged me Rs.420- as a penalty for keeping the device with us for long time and told us the account will be terminated once the penalty is paid. But they activated the service and nobody came to take the device. In November 2020, they sent their technician for retrieving the modem and they took it back. But I still get calls for renewal even without having the modem. They even charged me again Rs.420- in the January 2021. I paid that amount again to get the account terminated and it is still not done. Now again they want me to pay another Rs.420- as a penalty. I would like to get this resolved as soon as possible and the account to be terminated immediately.