Hi there Marcus
These are the people to speak to http://www.campingandboating.co.za/
, they are in Apex in Benoni and the shop in edenvale that Waynza is talking about (boating international) will refer you to them anyway. I think the lady to speak to is Zelda or something like that.
They do the practical at Rynfield dam and the Cat R you want to do will only take a day or 2.one day for the lectures as well. Hope this helps.