I have a 2mb line via Openweb. In Cape Town, from about 18h30 to 06h00 most days it gives me 1.7 - 1.8ms/sec. But during the day it drops often below 0.2mb/sec. For instance, this page took over 15 seconds to load.
In Montagu is is a fairly constant 1.1 - 1.3mb/sec, never faster
Is it congestion in the metropolitan area? The fact that the speed improves after hours and over the week-end shows there is nothing the matter with the line.
(I'm talking about international speed - Jhb and CT are much slower)