Unfortunately South Africa's public transport system is almost non-existent. These are a few shuttle services, ranging from backpacker to individual taxi-services which one can use from Cape Town.

1) Baz Bus:  Tel: +27 21 439 2323+27 21 439 2323
  
2) Percy Tours:  Tel: +27(0)72 062 8500+27(0)72 062 8500
    
3) Sean's Shuttle and Taxi Service - Airport and other Transport in Cape Town:

    Tel: 082 954 4867082 954 4867