Yes man..this is really the worst broadband service. I also had the same issue. They say that its postpaid connection but they take the advance rental. The pathetic thing is they terminated my service on 9 Oct, 09. My billing cycle was 21 - 20 th of next month. So I paid the complete bill for the last cycle 21 Sep to 20 Oct. Please note that my account was terminated well before the end of cycle ie 20 Oct. So, I have nothing to pay as I terminated the connection well before the cycle end date. Complete equipment was removed and I have got confirmations that my account is suspended. And I had also got the message that my security deposit will be sent with in 60 days of account termination.
Now see what tata indicom has done. When I called them after 3 months. They said that my security deposit is adjusted against my Nov-Dec bill. I was shocked to hear this. They stop the broadband service but the billing service never stops. They are reluctant to pay my security deposit. Please don't fall prey to this cheater.