HI, the problem is caused by agent. i have a friend have similar event like you. the agent told you that you just need work for 30 hours. but he also told the school you can accept work for 40 hours. many agent do like this. school pay agent for your salary about 15000 and in time. but the agent just pay you 8000 and delay it. Do not sign contact with agent. find a school directly. in hangzhou a lot school can give you work visa if you are native speaker. not difficult. the best way is find job from school. not from agent. on this website. lots school need teachers. especially native speakers.