How to make complaint to the school when your supervisor is going to ruin your life but you don't have any evidence on hand

A friend of mine was doing a master's degree in China, but he got married with his Chinese girlfriend immediately after his application for the master program had been accepted by his prospective school.

That means he got married before he started his master's degree.

Everything seemed alright and went smooth to him but he never knew that his supervisor got divorced on the date of his first year of wedding anniversary.

Something strange kept happening on his second year.

Some of his course papers which had been submitted to his supervisor were either lost (my friend said his supervisor did it on purpose) or returned without any remarks.

He was not aware of the unfortunate thing happed to his supervisor until some weeks later when he was talking about his frustration with his friends (including me).

He wanted to complain about it but he did not know how to do it because he did not have any solid evidences.

I don't know how to help him because that happened in China and bureaucracy is prevailing in his country.



So, if this happend to you in your country, not in China, what could you do to save yourself?