In addition to keeping notes from myspace or whatever stupid, invasive waste o' time site, your parents could keep a log detailing exactly what happens every day. I agree also about getting rid of the cel.
But your parents should also consider hiring a lawyer to go talk to the stupid morons running the class or school and explain that they are violating the law by not protecting your sister. Two or three hours of a lawyers time would be well worth it.
Homeshooling is just not an option for everyone. It worked for my son for a few years in the middle grades and was perfect for him, but neither of my daughters have ever wanted to homeschool. And many paretns cannot do it for personal or economic of other reasons, I don't think we should all be piling on to tell the kid to homeshool.
Neither do I like the idea of telling this brave young woman SHE has to leave school because OTHERS are nasty lawbreaking aggressors. What kind of message is that?
When the powers that be don't interfere, bullying only gets worse. It will not stop on its own as it is being, de facto, condoned by those in power.
There was an awful case around here that escalated into major ongoing physical abuse. It ended only when a lawyer was called in and threatened to sue the school. Newspapers got involved. It was a big deal, the school got sued, the town's lawyers clamped down on the bureaucrats running the school, and the schools finally got the message and have substantially reformed in this regard.
One thing is for sure: this will not end on its own.
Brave kid to be talking about it, though. You keep reminding your sister it is not her fault and has nothing to do with her. She must fight it, with appropriate legal measures. I'm so glad she has you in her corner.