If you are restricted to buying from one shop, then of course you can only select from the wines they stock.
I have frequently been asked to present tastings of RSA wines. RSA produces over 8,000 wines from more than 900 producers, and most are small.
I think that, to taste RSA one must have Chenin as as mcuh Chenin is planed there as the rest of the world altogether, Problem is that every style of Chenin is made so you’d need 9 Chenins just to show different styles, then what about the exciting blends that have Chenin as a component? And one must - IMO - show Pinotage, as RSA originated the variety and although excellent Pinotage is made elsewhere, RSA is its home and where the overwhelming number of plantings are. But again, it made in all sorts of styles (as we have read in this thread) - and as well as red wines, there are white Pinotages, sparkling ones, fortified and brandies.
I have looked through the RSA wines listed by your merchant and I would struggle.
I have not tasted either. Vriesenhof is winery owned by Jan Coetzee, who was the second winemaker at Kanonkop Estate (but Kanonkop’s Pinotage reputation was made by his successor, Beyers Truter). I can’t find this wine in Platter, neither is it listed on Vriesenhof’s website and I am also chary of its multi-vintage mix.
Pinot Noir is one of the recent successes, but the reputation comes from Hemel - en - Aarde Valley. I can see only two PNs, I’ve been to both wineries but if I tasted Fryer Cove PN it made no impression. I’ve not tasted the Chamonix listed here, but I think that’s the one to pick as they are making some excellent wines.
One wine I definitely would get is the Cederberg Bukketraube. This was - for a short time - at Waitrose in the rare varieties ‘Loved & Found’ series. It’s an 'orrible name to English speakers but Bukket means bouquet, and it’s a very aromatic white wine that on first taste seems sweet, but …
It’s an extremely rare variety, almost vanished and I think Cederberg are the only makers of a varietal version.
However, the selection at TWS is better…