Well Vodacom does have an online bill limit that you can set, but as I found out one month cause telkom took a while to install my line I got a R1000 bill fail on the notification that I set up. I phoned them and asked them about it and they said that it was not a guaranteed service.....I cried.
This is more aimed at those stupid vuvuzela ringtone and R5/day for a cellphone wallpaper subscriptions. I wonder who uses that anyway.... should be outright banned.