Enchanted Castle San Marino Montessori School

Last Thursday, my 3 year old kids came back from school with severe bruisings on the left jawlines and left inner thighs. School said the kids had conflicts that day and may have had bruising.
On Sunday night, after they took shower, I noticed the bruises were still there. What terrified me is that it didn't look like anything from a kid but a bloody adult fingernail print!! It's been five days, and it's still there. I asked my kids again and this time they told me that teacher did it. Next day, the director admitted over the phone that one of the teacher got frustrated, carried my kid. Since my kid objected to be carried, the teacher might hurt her. She talked to the teacher already telling her she shouldn't do anything physical to the kids.
Tuesday I took my kids to the doctor, reported the incident to the police and cdss.
Thursday I went to the school asking for an apology to my kids, the director changed her story and said her teacher didn't do anything. Director verbally threatened me that if I accused them for things they didn't do, they will report to the police.

A disappointing experience, I hope I will elaborate objectively, so that parents who only see five ? reviews can understand the real teaching and management situation of this school.
A. Problems with the main classroom teacher
My child was happy at this kindergarten for a short time. However, since the change of the main teacher, this teacher has been treating my child differently on a racial basis. According to her, she doesn't like my child very much because my child doesn't want to be close to her and would rather go to the Chinese speaking teacher if he has a problem. My child is bilingual, but the teacher said he is not very good at English, which is the first time I heard that from this teacher. Is this a child problem or a teacher problem?
The new teacher gave my child a minimum score of 1 out of 90% on the assessment form instead of "wait and see" or "not sure" for a situation that she did not understand after less than two weeks of contact with my child. Is this the practice of a teacher who loves and encourages children?
B. Management issues
However, the administrator of the kindergarten was not satisfied and would have preferred to accept a child who paid full price to replace us who paid half price, so when we spoke to the administrator about the teacher's situation, the administrator was biased and had no sense of responsibility or objectivity. In other words, they took the attitude of "go ahead and leave".
If you were a parent of a child, how would you feel?