Airtel — International roaming packs Charged without permission

I have been using Airtel service for years now and I am a frequent international traveler. Due to the lack of a good international service provider I have been sticking to Airtel. However for the last 3 years and travels I have spent a lot of money. My recent bills though have been in the range of[protected] rupees per month since single day roaming packages have been activated on its own when I have turned off international roaming from the fear of being charged. Please, would be greatful for the support.