Buy non-expiring bandwidth: If you don’t use up your 1GB per month of your ADSL bandwidth then you probably lose it since TelkomInternet’s policy (and lots of other ISPs) is “use it or lose it”. Changing your ISP will allow you to buy bandwidth and carry over any unused bandwidth.
NoFrills.co.za: R65 per GB (no help-desk; EFT only); R40 dial-up.
Then if you run out of bandwidth, top-up using WebAfrica (as above).
If you prefer to have No monthly charges then rather:Connect using GPRS/3G using your cell phone as a modem. Out of bundle rates: R2 per MB (else purchase a bundle for lower rates).
See here for info on connecting your cell phone to your PC: setting-up-your-pc-to-connect