Airtel Mobile Connection — deduction

I have recently (last week) taken airtel connection and I have facing a lot of problems related to internet services like on the night of 27 11 2009 at around 9:15pm I have called airtel customer care center to deactivate my internet but that person start my caller tune without my knowledge and they have deducted my Rs.20 without my confirmation its unlawful.

They are continuously deducting my money from my account without any approval and without any information?