CitySightSeeing website:
http://www.citysightseeing.co.za/

CitySightSeeing operates sightseeing tours with open top double deckers and a few singledeckers in Cape Town and Johannesburg. Johannesburg has one loop that passes by all majuor sites and museums. In addition a Soweto Township tour by minibus ("taxi") connects to the loop at Gold Reef City.
Cape Town has much more extensive services with two large circular lines (red and blue) and one shorter inner city loop (yellow, new in 2014). A single deck bus connects for a wine tour at Constantia. The company site provides all information.
The fleet end of 2014/beginning of 2015 consists of:
-a few (two seen) older Leyland -BUSAF doubledeckers on the short inner city loop in Cape Town
-Volvo -Busscar two-axle open top double deckers in Cape Town (seen: CSS 1 WP to CSS 6 WP)
-Volvo -Busscar two-axle half open top double deckers in Cape Town (seen: CSS 7 WP to CSS 9 WP)
-Ankai three-axle half open top double deckers in Johannesburg and Cape Town (seen: CSS 1 GP to CSS 3 GP and CSS 11 WP to CSS 19 WP)
-a Volvo -Busscar closed single decker for the Constantia wine tour
-two Volvo B7R-LE -Durabuild/CitySightSeeing (WINE 01 WP and WINE 02 WP)