A few weeks ago, I suddenly started receiving a "joke" every day from Airtel. I didn’t bother about it until I noticed one day that I was being charged Rs. 1/day for this. I had not initiated this service so I called them up and got it disabled. They however refused to reimburse the chanrges they had deducted without my knowledge (> Rs. 50). I pursued it for long through phone and email. I even wrote to their nodal and divisional officers (TRAI webpage gives their email addresses). They did not refund the amount till date.
One useful information I got from them. To check what services are active on your number send an SMS with text STOP to 121 and you will get the info on active services and how to disable those. I do this regularly now. I have also decided not to by any other service (broadband etc) from them.