Hathway — I have requested for service termination through calls multiple times but the service is not terminated

I have a hathway account with account ID-[protected], I have used this account for 9 months and switched to a new operator as I was not satisfied with the services of Hathway broadband anymore, I have received multiple calls from Hathway customer care asking me to renew my services. I asked them to terminate my account and the representives said I have to submit the device to which I agreed, But the Hathway team is asking me to pay a penalty of 450 rupees as I have not used any services for the past 6 months, This charge is not displayed anywhere in the portal and I have asked a written explanation and the statement as to why I have to pay the amount and the team is not ready to send me any written reason as why a penalty of 450 is imposed, Instead I am getting multiple calls from hathway and when I say that please give me a written explanation so that I will pay the amount the team is threatening me of legal proceedings and asking me to pay 2500 rs, I have received a message as a payment of 2500 has been initiated but know reason is mentioned, Please help me in terminating this amount. I have already payed device safe custody charges of 200 rs as displayed in portal and attaching the receipts. Please help in terminating the account and stop receiving any further calls and threats of legal proceedings, It is hampering my regular day to day work