Amazingly enough I actually had some decent service from these people. I rang 191 to check and see if they would be willing to activate international roaming, and before I could say anything else they had done it!
The advisor said I should switch my phone off and on and then to try dialling an international number. Did that and (don't know if you noticed it...) left a missed call for Bryn.
So now I can go off to SA and have my phone working. Would still much rather use my Vodacom number, so lets hope thats working. But I do at least have a backup.