Principle and some fellow teacher need conflict management experience

I borrowed a football to my son and his friends from a football club I coach at. They went to Marais Viljoen High school to meet a friend that goes there. They were playing soccer in the hockey field then were told to play on the rugby field despite others playing rugby and soccer on the hockey fields. I have to admit that my son and his friends were wrong in disobeying and had the ball confiscated. No problem with that. But then after hearing the story and approaching the office and even apologising on the kids behaviour they refused to give me the ball back. Stating to teach a lesson to the friend who the ball doesn't belong to. How will that teach him? It appears I have been a victim of pure arrogance and I must stress the way it was managed was unprofessional to say the least. I question the teaching ability of some of these people ...I won't mention names..also I would like the names of the guards on duty as one overweight guard manhandled two naughty boys yes but had no authority to do so and would like to press assault charges against this individual because he even threatened a young girl in the process. All these teachers could say is give the innocent guard a pat on the back for doing his job which I concur but they must investigate further about their other bully guard...