Honestly, a full year of consistent crying and not wanting to go is a long time, and the feedback from residents about how some teachers handle upset children is something I would not take lightly. I think it is worth weighing whether staying in this centre is the right fit for her, because some children do genuinely click better with a different environment or teaching style. You have already raised your concerns with the principal multiple times, so if things have not improved, switching centres might be worth looking into rather than waiting longer. You are her mother and you know her best, so advocating for her is never being "annoying" - it is exactly what she needs you to do.