Sadly, all of these strategies presume that the parent will agree.
When the child's response to all of these is to call their rich parents, who then tell the school "fire that (insert racial slur for foreigners here) teacher or I'll pull my child out of your school and convince my friends in the municipal government to harass your school," then nothing works because the child's behavior is reinforced by repeated proof that "I get my way because I'm rich and powerful."

The situation I just described has a name, and it's name is Beijing.