Tata Indicom — Billing customer wrongly

I have purchesed a new Photon+ connection from Tata Indicom on 27th of May 2009. My account is under the HSIA Freedom Plan, which comes with 10GB of free usage per month. When i purchased the plan i was not informed that the free usage was prorated. In addition the online system (which is the only way to track the usage) shows i have 10GB of free usage. I have never in any form of communication been informed the actual limit for free usage for the first month (except for the plan details which only states that it is 10 GB). Now the company has billed me for the usage over a prorated limit, while the actual limit or the fact that it is prorated is not communicated in any from. Also my line has been barred.
I have also filed complaint for this and also sent mails but have not recieved any response.