Jerry, You cannot get
C-band on a small 90cm dish. You need at least a 180cm dish, or even better a 240cm dish.
Yes, you can get a second dish and add a switch to connect two or more satellite dishes to a single receiver. You can add a single
satellite dish to multiple receivers with the right kind of gismo. Look through
Sadoun's site for theire switches and accessories. I would advise you to get a motorized Ku dish which is not too much trouble to hook up and then allows you to automatically switch to different satellites for the comfort of your arm chair.
Check out Lyngsat for what satellites are available to you and what frequencies... 3000 to 4500 (approx.) are C-band and the 11,000 to 12,500 are Ku band.
A great site I like that was developed in England is
Satellite Dish Pointer / Alignment Calculator with Google Maps which tells you what channels are available to you from which satellites, and the size of dish you need. This I hear is just in Beta testing... but does give a good idea. I don't know if it covers South Africa.
Best of luck...