South African Airways will charge you excess luggage, especially and in particular if you are not South African, on any flights and connections operated by them. They will also try their best to charge you excess luggage for the totality of the trip even if the SAA flight is just a short connection to your international flight operated by another carrier. What usually skips their mind is to inform you that there is a reduced fee per/kg for sporting equipment that is 1/2 of the normal fee. So if you get stucked with excess luggage be sure that they are using the sporting equipment fee and not the normal fee that they will use by default!!
Airlines part of the Star Alliance thing [where did they get the name from Star Wars??] seem more prone to bother you with luggage excess charges than other airlines.
One way to avoid this is to use British Airways [quite a good presence in SA] which has now a free baggage policy of one 23kg bag + a 32kg [up to] sporting equipment bag free luggage policy [for economy]. The downside is that you will probably transit through London Heathrow and that carries a high probability that your luggage will be delayed or even lost [talk about the Heathrow as "THE" European hub...pathetic].
Also, if you are renting a car [from Hertz for e.g.] be sure when you return it to ask for at least a pro-forma invoice that shows the amount of fuel used (like I did). Still it did not prevent them to try to charge refuelling fees on the final invoice although the car was checked on the spot by Hertz on return and fuel tank verified full.