Samsung Galaxy S6 SM-G920F
From this posts, you will be provided with link to official stock rom for your Samsung Galaxy S6 SM-G920F South African variant.
The firmware is flashable by the Sansung flash tool Odin. Guide on how to flash this stock rom into your Galaxy S6 SM-G920F can be found in this section:

[*] STEP WISE GUIDE FOR FLASHING YOUR SAMSUNG ANDROID WITH ODIN .

To check out other Samsung roms available on mobiPROX, click here.

DOWNLOAD LINK