You went to a private school, meaning you had more resources at your disposal to learn in a 2nd language, the average township student doesn't have that (which is what the HSRC study concluded), here is a report from Solidarity on the state of education in our country,
http://www.solidarityresearch.co.za/wp-content/uploads/2010/07/SAT-MONITOR-Education-enrolment.pdf it is shocking to say the least.
This is what the found of the class of 2009 (page 7 of the study)
The fact is that black students aren't motivated to go to school and the language barier plays a big role as concluded in Namibia, as for the argument that English is the international language of trade, yes I agree it is, however the average South African will most probably never work in customs or ever set foot outside of SA, the reality is that English has no use for him and that he has very little exposure to it in his home community.
their reading ability is also shocking