They did the right thing by rioting considering this...
"I picked up my son at midday [from his exam]. He started crying. I asked him what was up and he said a teacher had frisked his body and taken his mobile phone from his underwear. I was furious and I asked him if he could identify the teacher. I said we should go back and find him," one of the protesting fathers, named as Mr Yin, said to the police later.
Another of the external invigilators, named Li Yong, was punched in the nose by an angry father. Mr Li had confiscated a mobile phone from his son and then refused a bribe to return the handset.
People have the right of keeping a phone in their underwear!
Why would you refuse to sell the phone to the owner when he's buying it? That will only piss off customers.
From the same site, side link..
http://www.telegraph.co.uk/news/newsvid ... China.html