Not sure what that connection you have is, but if you access it over a lan cable then it is still possible to get it onto wifi, will check with a friend as I completely forget the name of the hardware, I know he paid about R300 for it. he had a wireless ISP, so antenna on the roof and internet into the house via lan cable. He had something similar to a router, 1 lan in and 4 out with wifi antenna.
I don't know how it works but we live on an institute's grounds (school, head office, college, etc.) and they are hosting a WebAfrica account (sorry, completely dumb with the terms) so they monitor and restrict the usage quite strictly and don't allow us to access through wifi (everything works through proxys) that's why we took 2 lines, one for hubby's pc and one for my laptop.
Think going the 'own ADSL' route might be the best at this stage. Any suggestions on good routers?