Airtel Delhi - Not satisfied with airtel

Dear Sir,

I am subscriber of Airtel 649 home broradband unlimited scheme with 512 kbs speed up to
6 GB and thereafter 256 kbs,my billing period starts from 5th to 4th of next month.

on 5th of evening ist day of billing cycle I received a message from AIRTEL that as per airtel fair usage policy
they are bringing down my broadband speed to 256 kbs. I wrote many letters to airtel and called them also explaining that fair usage policy should be applied after the usage of 6 GB and how they can bring down on the very first day of billing cycle,but every time they are taking different excuses sometime they say that your billing cycle is 21st to 20,when I insisted that the should check their record and it is 5th to 4th,then they said that because you have too much used internet last month that is why we are bringing down your broadband speed. I used speed on demand for RS.325 and paying for this to airtel which is also included in my usage but they are not ready to listen anything,is this not goondagardi by airtel? I was subscriber of mtnl for the last 30 years but daily airtel staff used to force me to shift to AIRTEL and now i am paying price for relying on airtel people.

(S.C.Gupta)