Thanks for writing in! Our data matches that of
timeanddate.com which shows that South Africa only observed DST in the summers of 1942/1943 and 1943/1944 and has not used it since. Are you able to cite a government publication, newspaper, or similarly reputable source that supports your claims to the contrary? Given that these lines in our data haven't been touched since ~1997 and common downstream data providers tend to match it, I would be very surprised if our data for such a populous country were wrong in this way and we hadn't heard about it long ago.