Thank you for the post since I was also struggling with this for nearly a month. Realised that PLEX does not have any e-mail technical support to help, albeit that the message says you must contact technical support. This dispite having a lifetime pass.
What is worst about the matter is that the marketing of Plex says you could watch their movies (on-demand) and live TV (e.g. Reuters or EuroNews) from anywhere in the world! Is South africa not "anywhere in the world"? How can local restrictions dictate what an American company should do? Therefore I agree with
@Brian_G there is certainly a possibility Multichoice/DSTV may have (helped) trigger this.