Some stuff from my sister-in-law, a professor at a college...
Your son is responsible now for how they do in school, not you the parent. Do the work, attend classes, do the reading. Showing up at the teachers office, a week before finals, and asking if there's any extra credit you can do to pass the class after missing most of the semester and not doing the work or taking the tests does not help. And having the parents call the Dean because the teacher is being mean does not help.