Consumer Redressal

I was an old subscriber of Idea and my number was 9552547092. I had activated a plan for Internet (limit 1GB) per month for Rs. 150. However, I stopped the usage of the plan in the middle of the month.To my surprise the amount charged to me for August for half the months was almost 5 times against the a few MBs of data. I tried calling the helpline on Aug 19 and Aug 21 2014 to understand and now it is being informed to me that I was charged on pro rata. However, at the time of deactivation the amount I would be charged on pro-rata basis in future was not informed. Nothing was told to me about the then existing outstanding.The exact amount for which I would be liable in case I was to deactivate then was not informed to me.I have made several complaints with the Idea but they have not responded whereas they disconnected my line.