This school has a lot of illegal workers who are working with L visas. The always drunk visa guy mr Che is now getting these people z visas aparently. No one has to leave China to do it and I thought that people could only get z visa's outside China. so who knows who is on the take.

Just to go into greater depth re L visa to Z visa renewal within China for the benefit of the readers - I've never heard of any FT with an L visa that was issued within said country being able to get it replaced by a Z visa within the country. That includes FT's employed by direct unscrupulous employers, like your school, as per your posted information, as well as the likes of Tianshuo Company of Jilin, an agent with a great deal of local clout.