What you describe is certainly true. But isn't it the bottom of the barrel?

One of the things to do would be to avoid the private training centre sector altogether and to look for jobs at public schools - middle schools, colleges, unis - instead.
However, there is no guarantee that even there they won't lower the pay while increasing the weekly teaching load at the same time.

The basic question is to find a decent school where they won't do these kinds of things with you. From their point of view, employing foreign teachers is very expensive for them. So, you may sometimes expect attempts on their part at cutting down their expenses - and that may mean less money for you!

Would you like a job at a uni in the public sector with only 10 hours of weekly teaching load, free accomodation, and and salary of 2000 USD a month? Well, you won't find it in China - you need to go to Sana'a University in Yemen; it's a full professor's salary and you need to have a PhD. And do expect not to be paid at all or on time for the first 3 months of your employment.

It's all relative....Anyway, my own time in China is over... Not interested anymore to work there, and I would still be able to find to find jobs like the one described above in the case of Sana'a Uni in Yemen, or even better ones.