Most ISP's are probably doing a great job under the circumstances. The main problem here is that Telkom has a monopoly on IPC and this is the most expensive part of bandwidth provisioning for ADSL ... This article explains it really well:
http://mybroadband.co.za/news/columns/102945-uncapped-adsl-why-throttle.html
If you think a bit about what is highlighted in this Article then it becomes evident that South Africa's big problem when it comes to fixed line broadband is Telkom. They are inflating the price of bandwidth when it comes to fixed line broadband. On-top of that they have their mindless forced line rental and really expensive ADSL access charges.
One would reason that the International bandwidth would be the most expensive part in broadband provision but it is actually a couple of times cheaper than Telkom's high priced IPC.
Pity not many people are noticing this or understands this. Telkom is an inneficient monstrosoty of a company and will probably milk consumers for many years to come... It would be awesome if there was some competition to break Telkom's stranglehold on fixed line broadband. Maybe fibre to the home will bring better days?
If you look at the graph in the article it would also be easy to reason that Telkom Internet could totally undercut all other ISP's when it comes to ADSL bandwidth due to them being part of Telkom. (They could price out all other ADSL ISPs and put them out of business and once again have total control and dominance over ADSL and keep on inflating their crazy expensive pricings) -
The current stranglehold Telkom has over IPC with Telkom Internet in the mix could classify Telkom once again as being anti-competitive?