Get correct GPRS settings:
MTN : Dial *123*13#
Vodacom : Dial *111# (Option 4 or 5)
CellC : Dial *147#

Make sure that the internet profile which you just received is set as the default profile.
(you should be able to set this in your "internet" or "connectivity" settings):
If you're on Vodacom: Select "Internet.GPRS", "Vodacom" or "Vodacom4me"
If you're on MTN: Select "MTN GPRS"
If you're on Cell-C: Select "Smartdata"

From your phone, go to http://m.mxit.com

Version to download : Motorola V400