Not only *speak* to someone higher up the food chain, but get a group effort going if possible. If the situation seems like it won't improve without some power-pulling, get students *and* their parents together. Go talk to either the Head of the Department, Principal, or both, and have something in writing (don't go alone to the principal's office, mind you.)
By doing this at my old high school, we got a few teachers fired/transferred, and others were suspended from teaching Senior Grades/HSC courses. So it definately can be done, but make sure you have extremely solid grounds for your appeal, and make sure it is your LAST resort.