Charging Bill without giving services – Tata Photon

Location/place: Pune

Name of company/service: Tata Photon

Hi,
I want to make a complaint against tata photon. I have taken a tata postpaid connection. But speed of internet is very slow, it takes minutes to open a page and continuously disconnect in between. So I have raised a request on their website to close my connection. No one has responded till now from their customer care. When I called today I came to know my connection is closed on 25th Jun due to no bill payment. But even after the connection is closed they are still generating the bills on my name. I have paid all the dues now. But i wanted to registered my complaint against them for charging the bill without giving the services. Please do the needful asap.
Thanks.