I don't actually know what the SLC is, but I assume its something similar to our HECS (Higher Education Contributions Scheme), the only difference I imagine exists is that ours is controlled by the Federal Government and yours is a private enterprise?
What your experiencing sounds very familiar to what has happened to our social security system that was recently privatised and remaned CentreLink, or CentreStink as it is commonly known. I know of people who have had their pensions cancelled for no fault of their own and the monkeys you talk to on the phone have no power to re-instate them, you have to wait a week for it to move up the chain, so you basically go without.
Hopefully, our glorious Government never sells out on HECS and I never have to experience what you are describing, as I've still got quite a bit to pay off. Good luck.