I would definitely be meeting with the teacher involved and the principal to straighten the matter out, as well as their expectations of children who have only been attending formal school for 4 weeks. All of that sounds so out of control and the reactions or the teachers sound like it was over the top. Maybe ask to see/discuss their behavior management policies/procedures. It sounds like way too much to expect of a small child who has been going to school for such a short time!
I must say though that early childhood and school/primary teachers are VERY different and things are dealt with really differently. Worlds apart!
I would be furious too. They have dealt with it all terribly.