Charging for missed call alerts service

Location/place: Hyderabad

Name of company/service: Idea cellular

Sir/Madam

I have a postpaid connection with Idea Cellular and they have activated missed call alert service.
I have requested them to deactivate it the next day only, and specifically told them not to charge for it.
At the end of the month I received a bill with missed call alert charges of rs 298/- apart from the usual plan and call charges.
My phone # is 9848372063 (primary a/c holder)
I have an add on line 9505478844 on which they had activated the missed call alert service.

I had called the Idea Customer Care for removing extra charges from my bill. They informed me that they cannot do it. Please help.

Regards
-Sai Hari