My teaching assistant at TA is severely unqualified to do her job

Good day everyone,
So here is the story. I'm an economics student and have a class in mathematical statics at a Bulgarian university taught in English. The professor who teaches the course is extremely old and uses a very familiar and accessible textbook, he doesn't speak English very well and his classes are utterly useless, so I don't attend them and read the textbook myself. The TA however is a completely different story because she is unqualified to teach the subject in the first place. Yes, she has a degree in Economics but apart from that her MAs and Ph.D. are in business administration. Usually, I use LaTeX so I'm extremely prudent about the structure of mathematical equations and can easily distinguish when someone never dealt with math formally in his life which is the case with my teaching assistant. She usually only solves the problem from the textbook (the problems are already solved for her in the instructor guide, which she uses without the appropriate authorization). She didn't show up for the first session claiming that "it was the first time" so she assumed it not being necessary for her to show up and didn't warn us prior to her absence. Afterward, when she started teaching her style of teaching was "hectic" at best, she would only ask people to show up on the whiteboard and solve problems chosen on a completely random principle, and they would normally waste 30 mins trying to solve them and fail and in the end, she would just continue with the next problem without providing us with complete explanation and solution to the one currently attempting to solve. She would choose the easiest problems and yet give us complex ones in the homework that were never even closely discussed before and the worst part of all Is that no one really understands anything about the subject except for maybe a couple of people including me. I scolded her for being chaotic and unhelpful, that she didn't provide us with appropriate feedback and rigorous solutions to the problems and she backed up by saying that "being mathematically rigorous is not what she is going for". On the homework, I told her that one of the questions is ambiguous and she said to me quote and quote "If you have concerns with the problems tell MIT, the questions are from their textbook in statistics, don't write to me ever again". I asked her about the precise name of the textbook because usually, MIT doesn't publish introductory textbooks in statistics and she said "It is a teachers textbook that a friend of mine who graduated there gave me", so how am I supposed to address my concerns to anyone at all if the textbook is the so-called by her "teachers textbook", obviously to no one, because such textbook does not exist, nor has ever been published by MIT in any form, she was just lying in a somewhat idiotic attempt to keep her authority. I just don't know what to do, no one cares about the subject because my classmates believe that "economics does not require maths" and I'm extremely lonely.