on 07-07-2019 09:59 AM
As far as my knowledge stretches, the change over to Vodacom roaming has already taken place. Not sure if you are aware of it, but you can identify Vodacom roaming if you see TelkomSA-R in the notification area of your Android Phone. If your phone finds no service at all, try reseating your simcard, restart your phone and if needed, transport yourself to a known good area for cellular signal and use the 180 number to call Telkom Customer Service.
This part of my answer is unconfirmed, though it is a possibility. If you were in an area where MTN network is dominantly available I suspect that the roaming agreement was recently ended by Telkom and will no longer be able to connect via MTN anymore.