I've managed to get many award fares in business class to JNB for 4 of us, and in school holidays to boot. Not an impossibility at all, if you can be flexible with days. And ringing BA at 7am usually gets you through to the very helpful Newcastle call centre; the London SAA centre is also many steps up from the ZA call centres.

SA is a fantastic destination. Whilst paperwork etc can be a bit of a PITA, it's well worth the effort. Definitely my destination of first choice.