When I arrived in South Africa some years ago, I was told that ..."yes, they
have diving clubs here" but no one that I've ever heard of has shepherded a
group of tour divers to S. Africa.  I hear troubling reports that the viz is not
good for the most part.

However, when I got to my resort on Mauritius after leaving South Africa, the
hotel was full of South Africans and some of them were diving there. Ditto, the
Seychelles.  I think that says a lot.

I would really recommend doing your own thing, it's easy getting around.
Here is a list of good dive operators.

Aliwal Shoal - It's Raggie Season at the moment

http://www.diveaeris.co.za/

http://www.meridiandive.com/

http://www.rockybaywatersports.co.za/

Sodwana Bay - Very good dive site

http://www.coraldivers.co.za/Index.html

http://www.sodwanabaylodge.com/

Other sites with more information and tours

http://www.divesouth.co.za/index.html

http://www.openwater.co.za/

http://www.scubaspots.com/Listings.asp?Location=SouthAfrica

Mozambique

http://www.simplyscuba.co.za/

http://www.seablue.co.za/

http://www.pomene.co.za/country.html

http://www.mantascuba.com/

http://www.marinesafaris.co.za/

http://www.guinjata.com/

http://www.barralodge.co.za/

Just a final note, the diving in South Africa is great, yes the viz might
not be the greatest in the world (at the moment 10 - 15 m) but the fish life
(Whale sharks, Raggie Sharks, Manta's and a sh.t load of other stuff) will
more than make up for the viz.  I was recently in Indonesia (Manado and
Lembeh Straits) and I think the diving you will get at Sodwana Bay will more
than beat that.

If you need anymore help let me know.

Paul Hunter
South Africa