What would you do?

I have a problem: my ten year old son, Jordi, hates his teacher.
His grades have dropped, he is misbehaving, I have been called a couple of times, and it’s getting worse.
My kid, who had been respectful, nice, and a good student, now has changed. But, how did this happen?
Here are the facts. Last year Jordi had a wonderful teacher and somehow he thought that he would have him again this year. Didn’t happen. Instead a new teacher came to the school, a “constructivist”. And this is what happens when you don’t get a theory, you do it all wrong. His “constructivism” consists of no-teaching. Yup, he doesn’t teach a thing because he thinks that’s what constructivism is about. In addition to his “methodology” he has, how shall I put it, his “ways”. Here’s an example. At the beginning of the year, Jordi lost his pen and he went to his teacher to tell him. The teacher response was: “That´s your problem”.
Sadly, the teacher has made more unfortunate comments and remarks, developing a tense relationship with my son. Now my kid is fighting back, he doesn´t want to work or obey any orders, he frequently talks back and responds to the teacher’s requests with a “I don’t want to”.
So, here’s the deal. I know that Jordi’s teacher is not a good one, rather, he sucks. But the truth is that in life, in real life, there are other people that suck too and we have to work with them, they might be our bosses, or our co-workers, or our in-laws, it doesn’t matter, we need to get along with them. And, of course, it’s hard to get along with people we dislike.
This situation opens many questions, but I’ll ask only three. How do we deal with this in a connectivist way? How do I teach Jordi to do that? What would you do?