Idea Cellular — Excess Bill for my phone

I am using idea service in Haryana circle for around 1 year. I use the phone on average basis like any other customer. I got a bill of around 3200 last month. I called up idea customer care, and they suggested they will reverse the excess amount. After 7-8 days, i got the message that it will not be reversed. Then I requested for porting my number to another network. I got a call from idea helpline again that they will reduce my bill by 2000 rupees. I agreed but I again got a call after around week that they will not reduce the amount. In the meanwhile again this time my bill has shot up to another 1800 approximately. Recently changed my package to vaue package and the site mentioned that I would have to pay 599 per month. No one from the phone company told me that they will charge 4 rs per MB. The helpline is not very supportive, obviously each time I call them up I have to explain the problem and then finally the complain does not yield any result. Kindly suggest what should I do, and help me.