Not stopping connection and wrong billing

Location/place: Kolkata

Name of company/service: Tata photon

Dear Sir/Madam

This is in regard to a Internet connection provide to me by TATA DOCOMO – account number -943340706.

I have not been using this connection for the last 3 months as I was facing speed issues. Dispite of constant reminders about speed it never improved and I had to request for closure of the account 943340706, with them.
I sent several mails . Called up the customer care innumerable times but nothing happened and I have been paying bills month after month despite of not using the Internet connection in this period.
Still I have been getting constant reminders about bill payment for this month too.
Something is seriously wrong with these people.

Kindly do the needful to stop this irating behaviour from them

Regards
Umashankar Singh