Hathway broadband and internet hyderabad - not terminating my account

I was using hathway internet services in Hyderabad for a year till may ****. so due to covid I have to leave Hyderabad , so I called then and told that I have to close my account and return the devices. a guy came on June *,****. and he took the devices and took a selfie of me handing him the devices and told me that I will be updates in ** hr. when I asked for receipt that I returned the devices he told me that I will be updated through mail or message. I believed him because from the start of my connect hathway never gave any receipt through paper they only sent me mails like bill payment . and for the next two months I have not received any call or mails from them. but from past * months i have been receiving calls and messages to renew my account . even after telling that I terminated my account . they still keep on calling. then called to their nodal office and told about the issue. now they are saying that my devices are not submitted. to close the account I should submit the devices or pay **** amount. and * days ago a guy from hathway customer care called and asked me to renew my account, i told him that I terminated my account. he told me that if u don't want to be bothered with calls and message's u need to pay *** and in **hr your account will be completed terminated and your amount will be refunded. now they are not answering my calls and for the amount i payed * days ago the gave a fake bill raised for month of august ****.