Airtel — mobile number not deactivated despite many requests

Address: Bangalore, Karnataka

I have raised a few requests to deactivate my mobile number, until now my number is not deactivated and i am getting the bill every month, which i will not be able to pay the bill as they not deactivated my mobile number despite many requests. This very unethical practice followed by airtel not to deactivate the number and generate the bill to customers. Please help in this matter. They are customer support team are rude to talk.

Thanks and regards,
Gerald