I am green with envy. South Africa, data is so expensive I literally only check my WhatsApp messages when using cellular networks. Everything else I do when I connect to ADSL backed WiFi connection. Here are two deals being advertised on Vodacom (vodafone), the largest cellular network in SA. Per month. (Yes it is MB not GB).
You can get an LTE data-only SIM capped to 1GB for $5/mo (ZAR 67) from Axxess[1]. Granted - it's not unlimited and doesn't include calls and SMS, but it's much better deal than Vodacom - for data.
https://www.vodacom.co.za/vodacom/shopping/plans/plans