I've got to agree with you Paul and I think in Telkom's defence (never thought I'd ever type that) their system of allowing you to monitor your ADSL usage via the website in real time is really awesome. With regards mobile there are far too many people who are not aware of the high data charges once they cross the usage threshold and then they feel the pain (sans vaseline) when they are hit with a massive bill.
Surely in this day and age an online monitoring system for mobile data isn't too much to ask?