Bakkie, big roll of cable on the back, splice one end to your building in JHB, drive to CPT, splice the other end. You are up and running. On the drive back dig a trench and bury the cable. EASSy really.
Same process for undersea cables only you need a RIB not a bakkie, and there is no need to bury the cable - which is why its cheaper for bandwidth to London.