About 2 years ago I registered a limit with Vodacom when I loaned a 3G card to a friend, subsequently got a bill for > R3k and when inquiring helpdesk said they can see the limit was activated but it was 'immediately thereafter deactivated by their system'. No further explanation possible, but I was still liable for the amount despite the failure on their side as the data was consumed after all.
I ****ing kid you not!
Asked for an investigation but (surprise!) never heard from them again, wrote it off as school fees but I closed my 3 accounts (had one since 1996!) and the only agreement I still have with Vodascum is a 79c/min prepaid sim.
If you trust the devil you will get burned!