Well, we'll gonna wait quite some time for anthing to happen - at least a year, maybe two. Which ISP is gonna shoot their cashcow? None I know. Checkmate!
Try bargaining with Cybersmart - R499-00 for 10Gb + grow for life (gives you an extra 2mb or 3mb per day) + nightrider (download between 1am and 7.59am) and you can use 35Gb per month. No other ISP can beat that. With or without Seacom.