cheat and excess billing

Location/place: Delhi

Name of company/service: Bharti Airtel

Sir I got a connection of Airtel 6-7 month ago as a part of my company policy i.e. Cug 99 plan. According to plan my billing cycle were 6th of every month. But I had to submit my bill against my reimbursement till 4th of every month. So that I requested to Airtel customer care countless time to change my billing cycle but they did not respond and charged late fee on my no. While it was their fault. After that there was 1000 excess billing in novermber month on the name of gprs. But I requested them contacted to their nodal officer regarding that but they didn’t respond positively. After all this I got the call from them executive of Airtel regarding bill payment. I told them a lot more time about all the above problem they were only have the words ”my system is error free” nothing else they response positive. After all they they stopped my services without information while it was my life line because being a journalist I need the mobile too much for my profession. I faced a lot more problem. Daily I am getting all the repeated tape of their customer care executive. After that they were saying how much you think the real and actual bill. I told them that I am ready to pay the bill i.e. I will not pay the late fee and not that excess charge of gprs what I have not used.
They became ready and said me you got a waiver amount of rs 2094 and rest 3200 you have to pay. We will start your services. I asked them the proof of waiver they send me a mail and I paid the amount of rs 3200 and they started my services. But within 24 hrs the services of my no. is again withdrawn. So I will like to have a leagal action against this cheat, fraud and the mental pain what have been made by them.
I hope I will get justice.