Is it normal for vocational schools to take a student's word over a teacher's, if the teacher is inexperienced?

Not too long ago, I was an adjunct instructor at a vocational school. I (to my deep regret) told the cl that it was my first time teaching, which basically opened the door for all kinds of problems. For the most part, the cl was ok, except for one student who constantly whined, complained, tried to negotiate grades that were not earned, and pulled countless stunts trying to push as many of my ons as they could. In short, this student did everything they could to make the cl extremely (and unnecessarily) challenging, knowing full well that I was uncertain and vulnerable. To make a long story short, it didn't seem to matter to the person who hired me that I was on good terms with the rest of the cl - just that one irate student (who was already known for being a royal pain in the...) bickered to no end because she COULD. The person who had hired me wasn't even interested in hearing my side of the story (and this was after me having gone to her early on in the course, voicing my concerns about the troublemaker). In addition to all of this, I have yet to get a straightforward answer (as if I'm supposed to already know why I'm not being asked to teach again). So, does anyone know what's going on here?