This is scary... 
Source...
No more roaming for me.
“Bill shock” is a growing problem for SA travellers. They go overseas, and, before they know it, they’ve run up a bill of thousands of rand — without even making a phone call.
The problem is, as with roaming voice charges, the mobile operators impose exorbitant fees for roaming data — in some cases more than R100 000/GB! And with smartphones, which are constantly polling the network looking for updates to e-mail and other services, consumers can quickly run up monster-sized bills.
MTN, for instance, charges in minimum increments of 25KB. It warns in the small print on its website that smartphone users must disable all data features before they travel abroad.
“Failing to do so will result in you being charged the minimum billing increment each time your device connects to the mail server, even if no new mail is sent or received,” MTN says.
And those 25KB increments are worth their virtual weight in gold. Roaming in Europe, for instance, costs R2,70 per 25KB. That’s roughly R108/MB, or R108 000/GB. North America is even more expensive at R140 000/GB.
Vodacom and Cell C aren’t much different. Roaming rates in Europe are R128/MB, or R128 000/GB, on Vodacom.
However, Vodacom charges its subscribers in smaller, 10KB increments. Cell C’s billing increment varies, and, although it’s rates are harder to compare as they also vary by country, its data roaming rates are roughly in line with the high fees charged by the other two operators.
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Source...
No more roaming for me.