You are employed to hire teachers so you select a few reputable websites and persuade your
bosses to pay for advertising there, only to find out that about 50 other sites have
taken your details, manipulated them for their own criteria and posted the jobs
available. Then your boss complains that those sites are full of nonsense and will cause
him/her/the school issues in the future.

You should have only advertised the jobs through a couple of reputable Chinese recruiters. Then the name of the school wouldn't have been divulged online in a specific advertisement that is able to be hijacked. As you've botched things for your school, you should move on. Next time, you'll know how to proceed in order to avoid the pitfalls.