This is eight ways to fucked up but I find it terribly disingenuous for her to have any morale outrage at the system that she herself as the supposed parent, was not staying on top of. So for three year you never asked the questions that would give the clue that your son is not doing what he should? If she doesn't care at the time, then it is hard to expect the teachers to care (or be forced to do the right thing) either.