Airtel — denying it is their no

Address:

Bangalore, Karnataka

I have been using this airtel number [protected] since a year. Some few days back when i spoke with airtel customer care where they denied that the number is theirs. I wanted to inquire why airtel gprs was activated automatically and why my balance was being cut. Now there is no clue about where to complain and if there might be security problems later on. I have provided all the necessary documents while taking the sim.
Please look into this matter.
Thank You.
Peter