My french teacher is the worst!She disrespects everybody!!!What to do?

Today she told my brother that my mom was disrespectful, rude, obnoxious,and a backstabber. My mom, trust me, is absolutly none of those things!!!! We have had problems with her before. One time in cl I freaked out, and had a meltdown, and then I wasn't aloud to go to french anymore, because I had a note. Well, after that got sorted out, I had to go back to french, which they switched to our clroom. She is horrible, she said she wasn't here to teach us french..well, what the heck is she getting paid for??? She tells us about her ual life, which, being in gr.8, we really don't wanna hear why she left her husband. She has threatened to chop off kid's heads, and the office doesn't do anything. I'm am one of the most trustworthy kid in the school, and they still aren't doing too much to help us out. My mom says if the office doesn't do anything, she is taking it to the board office. But what else can we do to get this teacher fired in less than 14 days????