Maybe they NEED you to work 9 hrs because they don't have anyone else. Maybe other people told them not to schedule them for mornings so they fill the schedule with who is available. If you ONLY want 4 hour shifts, then you need to make sure your availability is in writing. They aren't mind readers.
Whatever.... I don't want to be there anyway, I hate this shyt so much...mothafukkas telling me what to do...like I'm a bytch