OMG this was exactly my experience, or nearly so. I was there in the winter of 2013 and taught for her without taking the certificate course (I am already a certified teacher in the US). She proceeded to humiliate, castigate and compare me to the other students who had paid her course fees and then told me that if I wanted to continue my (trying) to teach there I would need to pay two weeks of course fees for this “TEFL” class. Then she let me go after 4 more weeks of torture. I so angry, but also decided right then that I was not letting her define Mexico for me. I packed my cases, cleared town and moved to Oaxaca to spend 13 more wonderful weeks just learning Spanish and falling in love with the Mexican people. I even had a job interview while in Oaxaca and mad a positive impression. But I was I so traumatized by the whole affair that I decided to leave teaching at that point. I blamed myself but it sounds like my experience was far from unique. I did write to Lonely Planet and urged them strongly not to include her school in their listings in the next edition of the guidebook and they DIDN’T:). I am also back to occasional teaching and earning good wages and really high marks.