Tata Docomo — Not cancelling my connection

Address:

Tamil Nadu

I got new Docomo connection on October 2010. Within one hour I called the customer care and asked to provide me unlimited gprs scheme as available in airtel and aircel. But they said that option is not available. So I asked them to disconnect my connection. But they did not disconnect and sent the bill for October and november. I again called the customer care and asked them to disconnect my connection and also informed that i did not use their connection not even for one hour. i also sent email regarding this. but they did not disconnect and sending bills every month. as usual i am calling and sending emails but they are not disconnecting. this is going till this month February. i donot know what to do?