Look at this website under services. They seem to have a list of hundreds of flying schools there.
http://www.aviationdirect.co.za/
My experience was not that good when it came to service from some of the major training facilities in the Johannesburg area. It seems safety has taken a dive. Most of there aircraft I was looking at hiring were old and in bad shape and I soon changed my mind. Be careful who you go to and pay as you go, Dont put money upfront!! Safety would be my main concern and there standard of maintenance. There has been an acccident in the last week with one of the main training facilities in SA.
The great thing is its an amazing place to fly and a lovely country to see from the air. Good luck in your training and have fun!!