First of all, talk to the teacher yourself. Let them know that you don't like how he treats children. He is not obliged to love all children, but that does not give him the right to bully a child. Try to do it in the correct form. Maybe the teacher just lost it or this behavior is not typical for him.
If the conversation had no effect, and you suspect that "reprisals" in relation to your child only intensified, go to the head of the kindergarten. Explain your position. Don't forget to present their claims in writing. And specify your requirements: whether you are asking just to understand the conflict, influence of the teacher, to punish him, to transfer your child to another group.
If you have not found a common language with the Manager, she ignored your complaints, and everything remains unchanged, then send a complaint to the Department of education of your city, which provided details tell us about the abusive actions of the caregiver and the complete failure of the head. If you enlist the support of other parents and write a collective complaint, then you can count on its prompt consideration.
Must attach a medical report about the traces of physical violence (if any, and if recorded properly). In this case, a copy of the complaint can be sent to the city Prosecutor's office. This offensive on all fronts will lead to action.
If your complaint relates to financial extortion or inappropriate use of funds, speak to other moms and dads. If they refuse to confirm such facts, it is unlikely that your complaint will react. They can ask for a receipt on delivery of the money or something to fix this in my own notebook.