I've just received a technical report from Cell C explaining that my upload problem is due to interference at my tower (only affects uploads). They also say "once the interference is found in the area the upload speed will be back to normal". No indication given as to when and how this will be resolved.
Interesting, thanks for the feedback.
I have been trying to think what could be the cause of such bad upload speeds. The way I understand it, the backhaul links are all symmetrical, so say for example your tower has 10Mbps of backhaul capacity, there will be 10Mbps available on the downlink
and 10Mbps available on the uplink.
Most people are downloading and 3G/HSPA modems can download faster than they can uploads, so there should always be spare capacity for uploads.
I guess it could happen that the downlink may be so saturated that the requests for more data from the speedtest.net server are being delayed.
The other thing that occurred to me was back when MTN rolled out 1.8Mbps HSDPA in 2006 they
had to switch a section of the upload off in order to fix a problem, they only fixed this during the roll out of 7.2Mbps HSDPA at the end of 2007. During that time it was faster to upload on EDGE than on 3G/HSDPA!