Well, my Telkom signal nearly dies about an hour into loadshedding in Garsfontein, my friends Vodacom signal almost dies shortly after loadshedding starts. I think we just connect to further towers as the local one dies. In your case something probably broke in the tower.
Yeah, their service is shocking today... I'm dropping signal constantly, what's weird is that when I disable the mobile data on my MiFi router, and re-enable it, I have connection for about +- 5 minutes, it then drops again. It's not like my signal is bad either, I get full bars when it's connected.