You can sell privately, but advertising is the main thing. I know a couple of people now who have sold just with word-of-mouth, never even bothered to take pictures or post online. So it can be done.
I guess it depends on where you are. I get estate agents phoning me at least twice per month asking if I would like to sell. I suspect if I were to list on Private Property I'd get responses fairly quickly.
A while ago while I was looking for houses, I noticed that Eazi has a fairly attractive model, they have a flat rate of ~R40k IIRC, which in my mind is a very reasonable price for the amount of actual value added.
Sure, an estate agent adds value, but property is getting so expensive these days that 7.5% of the average selling price of a house ends up being a crapton of money. Also I've seen some listings where the agent was clearly incredibly lazy - poor quality photos, complete lack of information, not helpful at all. So I can completely understand why someone might try to sell privately.
There was a thread on this a few years ago - I can't seem to find it now, but one forum member put together a bit of a how-to.