Have you been able to use your phone in South Africa on this trip previously? This is to seek evidence that your roaming facility is known to work. What do you mean by "add in call rest of world"?
Potentially you have 2 issues...
1: PAYG lines are subject to the hibernation policy which requires chargeable usage at least once every 179 days to avoid hibernation - with a further 90 days grace before outright disconnection.
2: PAYG lines need to be first used on EE's UK network before roaming is enabled for use abroad.
If you have not satisfied condition "2", and you are currently abroad, then condition "1" is still required but you will only resolve your catch-22 by using your EE SIM in the UK to resolve issue "2"
You mention having "roaming turned on", but I suspect you're referring to the data-roaming menu option, which just enables data use whilst roaming. Roaming itself is an account-level setting enabling your SIM to connect to foreign networks - for voice-roaming, data-roaming & text-message-roaming. If you have previously used your ohone on a South African network then you can assume roaming is already enabled, and I'd suggest manually selecting a different local operator.
