I think you should be very happy that you can't use data in South-Africa as it will be very expensive. Fortunately the usage of data will be blocked as soon as the costs reach €60,- unless you give the order to keep using data. I would advise you not to do so as costs can get very high. The majority of hotels and lodges have wifi.
Hi @LezanneDup and welcome to our forum! WJB's made a good point, roaming in South Africa isn't cheap. Internet is €2,50 per MB, unless you’re using a bundle (Voordeelland buiten EU). If you’re using a bundle or are okay with the extra costs, then check your phone settings, specifically the network settings. Try different providers there and see if any of them will work.
If that's not the case, there's unfortunately very little I can do. We partner with South-African providers there and are dependent on their network. Hopefully connecting with a different provider there will do the trick!