Airtel — airtel activating services and debiting amount without my permission

I had a hdfc smart pay setup to recharge my airtel number with rs. 100 every month. I don't know how but airtel manages to deduct money from my account without me noticing it. They send you a lot of spam messages and among those messages, some message will say that "thanks for choosing musiclate on your airtel mobile. You have been charged rs. 99.0 for 30 days. A/c balance: rsxxx at 00:48. To deactivate, call or sms stop to 155223.
I have no idea, when it gets activated and when the money get debited. At first, i ignore it. But incidents like these have happened to me many times so i have decided to raise my voice against them. They will pick some random service like: musiclate, bollybazar etc to rob people of their airtel balance.