Reliance Netconnect Internet — Billing without proper service

I have been using reliance net connect Platinum plan ie 1500 per month plus taxes. I was offered datacard along with my new Compaq laptop. Even after that I have to pay Rs 3800 plus amount to register for internet connection. As my plan initially was pay on use plan. As I am frequent user of internet connection, i requested them to change my plan to unlimited ie; Platinum(Rs 1500+ taxes) as the Rs3800 was given in advance for 3 month rental and was not supposed to pay first 3 months bill. But I was charged from the first month onwards, when i inquired about the same with reliance customer care, they told me that due to the change of plan opted by me, I have to bear the loss of Rs 3800 plus without any proper reason. Two month before I opted to disconnect my connection. I didn't pay the last month bill as I was not given proper service as they promised. Now they are just sending bills and frequently calling me over phone and asking me to pay bills. As a citizen of India, I want justice without any flaws.