WonderConnect does not provide any unlimited data eSIM plan for South Africa. The largest plan they offer for that country is a 50GB bundle that is valid for 30 days.
If you need a high data allowance, you could consider a fixed 50GB or 20GB 30‑day plan, which can be more cost‑effective than purchasing pay‑as‑you‑go credit if you expect to use a lot of data during your stay.