Airtel — Airtel postpaid Connection

Address:

Nizamabad, Andhra Pradesh

Hello Friends
I am using Airtel postpaid Connection from 2001 I am a regular customer of Airtel I have a total of 6 connection I love the the service but now I am getting problem from it.
From last few years Aitel has online paying option so I am paying my bill online from past 4 year without any quries because as I know airtel never cheats I use to pay my bill before the dud date as we know we will get out bill after the due date and when I saw my bill few days back I was really chocked by seeing
International outgoing calls package
Unlimited internet usage both were activate which I never do when I went to the local office here they said me to go in head office in Hyderabad and I have a personal talk to there manager and when I saw the details it shows that International calls is activated from past 7 months and and Internet is been activated from last 3 years which I never know we trust airtel so our company workers use to pay is regularly the amount directly and when the airtel office manager saw the details it shows from last 3 years I never use even a single kb of internet as its my business phone I will be on calls only and the amount was of Rs 18000/- and other was of international calls which was around Rs 750/- they booked the complain and later I got a call and they just refunded me 750 as if I am fool and said we will not give you that money as it is too old and suddenly they change saying that in unlimited plan we cant trace how much data is been traced.. and just made me fool
So is there any one who can help me I am ready to go anywhere also I am ready to book a case again airtel please help.
Thanks.