I have been in this boat. A school (without informing me) was in the process of switching my visa from a Z to a F visa. "It's okay, we have good connections with the government." they said. "No, it's not okay!", I replied, "I demand a Z visa and if you don't give it to me then I am illegally fit to be working here." "I want my passport back now, or I am calling my embassy to let them know what you are doing with my passport." I got my passport back quickly, I left the school and found one that hired foreigners properly.

Never trust a Chinese businessperson/manager in the ESL field. In my honest opinion, within my experience, their souls are blacker than a thousand eclipses. The most deceiving, cheating, lying and overall worst people I have ever met, all fall into this category. Trust your fellow foreigner teachers, trust government websites, and your instincts before you ever trust one of them.

TEO