Some Parents Need Help

I have a severely learning disabled boy in one of my Math C classes. He gets extended time on exams and is allowed to finish his exams in resource room. Even with this extra aid, his highest grade has been a 20. His resource room teacher wants to help him, but he will not allow her too. I arranged for one of my advanced placement calculus kids to sit with him, tutor him and even look over his shoulder while he takes an exam. So far, there has been no improvement, although the boy that tutors him thinks he might be able to get the stuff in the end. I would also like to add that my class has 34 kids in it, some of them, slightly on the difficult side. Anyways, I'm not complaining about the kid. He is a good kid, tries, and I am hopeful that by the time the regents comes around he will able to learn enough to get a 55. The problem is his parents, or more precisely, his father. They came to see me this evening. They were obviously upset about his lack of progress in math. I explained the help he has been given and then told them I was at a loss as to how to help him. At this point, the father said "That is not the answer I want to hear" and got up to leave. I told him to go see my chairman, maybe he could offer advice. The father just kept walking never looking back. I like this kid. I would really like to see him succeed. I've gotten kids like him to succeed in the past. I've never had a parent treat me like this. I'm a big girl, though. I don't like being treated like this, but I can take it. I just hope he is not being verbally abusive to his son at the moment because of the boys deficits in mathematics.