TheHxckid, a friend of mine had the similar issue with steam not functioning after his international cap has given in. Steam validation/authentication uses very little bandwidth, however playing steam games can take like 30MB+/h (depending on your rates that you've set ingame). For splitting traffic you need 2 separate Internet accounts...
That's why he now bought a 10GB OpenWeb local-only account (for R69pm), which he is using in conjunction with a Telkom mixed (1GB int / local) account. I have set up a Linksys WRT54GL router (that runs DD-WRT 3rd party firmware) behind his D-Link DSL-2460U ADSL router, with Gatecrasher's scripts (see
http://mybroadband.co.za/vb/showthread.php?t=81315) running on the Linksys one to route all the local traffic through the local-only account.
If you don't have a router capable of running DD-WRT firmware, you can try using RouteSentry (see
http://mybroadband.co.za/vb/showthread.php?t=39234) to do the same (routing local traffic through the local-only account), however the RouteSentry type of setup gets complicated when you want to give more than 1 people access to the Internet. To do that you either have to run a proxy or VPN such that the other users can connect to the Internet via the PC that's running RouteSentry OR you have to setup your router in half-bridge mode (which I would recommend), such that the router dials one account - thus allowing people not running RouteSentry to connect to the Internet using the account that the router dialed.
Another way of routing local-only traffic would be to use IPCop (see
http://mybroadband.co.za/vb/showthread.php?t=64649)
Hehe, there's one scaly method remaining for playing local steam games

That is if you have a friend that has International cap left, to ask him to host a VPN for you. Unfortunately this would require a good knowledge of routing tables for him to setup the VPN such that ONLY steam authentications can go through his VPN.