I don't know what the hell those cretins at Karoo are doing, but for months my connection has been predictably dire. Every night at roughly the same time, my connection fluctuates and disconnects every 5-10 minutes. Trying to use the internet and IM programs is immensely frustrating.
Something needs to be done, and soon. Maybe a protest would sort things out?
You might have a problem with an unstable line. Try giving Karoo a bell and asking them to reduce your line profile, see if that works.
Cheers
Dyls