I have worked in Korea and Thailand. I have to say that the practices I witnessed and heard about in Korea were a lot more serious than Thailand and they always involved a lot more money.
At the end of a contract here the school bumps you a months salary, it is a c**t but its not the end of the world 30,000B or so. In Korea I knew of schools that had bumped the whole of the final payment which would be the severance bonus (1months salary), the final months salary and the return airfare money, you could be looking at 2500 pounds or more 150,000B+.
That stings your pocket. I survived 6 months in Korea simply because I was green and had no idea of what to expect the school to be like. Looking back now I know that I can return if I want (if I am allowed is another factor) knowing how business are operated there.