I would just do what Guy Betsy said...find a Canadian TA and get your ticket before you get there. It is a whole lot easier.
You can then go out and enjoy yourself instead of looking around for an agent while you are there.
I did some checking while I was there and got the same answer as another poster. They indicated that I must present my card there and that they couldnt Fedex it to me in advance because of some law there prohibiting that.
For something to do if you have a couple of days...buy a ticket from JNB to SZK. It is about $200 round-trip and a 55 minute flight and go on a two night safari. You will see the Big Five in those two days.
I have been there twice already this year on RTW's.