Tata Telecommunications - Tata Tele Broadband services billing after disconnetion request

I had written to Tata Docomo to close the account becausethe connection was frequently interrupted and the speed was too low.After disconnection request neither bothered to disconnect nor resolved the issue. instead harassing customer that * months bill is pending. I have called the customer care service also to disconnect inspite of disconnection request they sent bills for * months and calling everyday to clear the pending amount. After disconnection email i have not used the services neither their complaint which i raised was closed. Now after * Years Tata teleservices is communicating will be processed legally.