I don't have any specialized knowledge of the state of FTA in South Africa, but here are some general tips that come to my mind.
First, I'm guessing the population density of your area is relatively low, so its likely that though there may be satellites "visible" in your hemisphere, their beams cover areas north of you, namely Europe, Middle East and Asia, places north of the Equator. Start looking at Lyngsat and Tele-Satellite and see what satellite beams cover your area to see if it is worth your time.
Now if you find satellites and channels you're interested in, you'll start collecting equipment. Unfortunately, that 90cm dish of yours will not be sufficient for
C-band reception. Bigger is always better of course. If you can mount a 3 meter dish or better, go for it. (I just looked at Lyngsat, and it seems the 68.5E C-band signal needs a minimum 180cm dish.)
Also, I'm guessing that your best chances for intercepting C-band signals will be from international birds. Here in the US, most non-DBS (direct to home signals) of C and Ku band are horizontally and vertically polarized (linear). International satellites usually use circular polarization, so you may need a C-band circular feed, or in a pinch, a linear feed with a piece of dielectric material placed in the feed with convert it to receive circular, with some small signal loss.
You mentioned your view of the sky. In the Southern Hemisphere, you'll need a clear view of the northern sky. Get your dishes motorized so you can sweep back and forth, from horizon to horizon if at all possible is optimal.
If you go C-band, there are combo-feeds that do C and Ku band. Again make sure the polarization (linear/circular) is taken into account for your needs.
Good luck!