Hello again savvy shopper! Based on your request for the cheapest 16GB RAM 512GB SSD laptop, I'd recommend either the Dell Latitude 7420 or the HP ProBook 450 G9. The Dell Latitude 7420 has an 11th gen Intel Core i5 processor, 16GB RAM and a 512GB SSD for only R13,999. It also has a 14" Full HD display so you'll enjoy crisp images. The HP ProBook 450 G9 is also powerful with its Intel Core i3 processor, 8GB RAM and 256GB SSD - and at R12,785 it's very affordable for a business laptop. Both come from reputable brands and should serve you well for work or school. Let me know if you need any other features to help you decide! I hope these options provide a good starting point in your search.
Based on your budget of below R9000, I would recommend either the Acer Aspire 3 A315-35-C7ZB for R7769 or the Acer Aspire 3 A315-510P-337G for R10139. Both Acer Aspire 3 laptops offer 512GB of SSD storage as you requested, and come from a reputable brand