Airtel — international roaming activated without my consent

My mobile number [protected] got international roaming activated, without my consent. Now i have been charged rs.4498 + tax as one time charges. Further rs.470.20 as usage charges (In next bill).
I made complaint about this and asked for waiver of the amount, through e-mail. There is a lengthy activity of mails and replies. But there is no solution for me. They are adamant about getting the amount paid by me.
When i visited indian customer complaints forum, i saw so many people made the very same complaint and nobody got any remedy.
It seems to be a regular practice by airtel and this is like pick pocketing from the customers.
Can you guide me how to make this as a complaint to trai or can i get solution for this through consumer court.