What type of kindy is he in - a department preschool, or a private child care facility? It varies from state to state, but in SA, his kindy teacher would certainly be well qualified if he is in a government- run preschool. I personally feel like preschool is a job you need to be good at and love doing it to manage in the profession - but I have also seen my fair share of crap teachers. It's just too hard to say which is which in this situation. But it seems like they are finding your sons behaviour challenging amongst the group of children in his class. If he has an occupational therapy report,this would suggest he has been visited at preschool by an OT to look at how he functions in the preschool environment. Even if the teacher IS rubbish,the OT is almost definitely giving a very objective report.
I agree with LoveLivesHere - see your GP, try to get appointments with an OT, & see what they say & if there are behaviours that need addressing. I have a 3yo with some very challenging behaviours. I am seeing an OT to get her help now, because as an Early Childhood Educator, I really know how valuable that early intervention is. My goal for her is just to have her functioning normally in a group education setting, & I know her early interventions will help with this. I think until you chat to his educators & find out what he struggles with, you wont really have the full picture. Write a list of questions & ask them everything you can. Observe him in the group setting & see if he seems to be behaving differently from the other kids.
And lastly, from my own experience with my 3yo DD - some people see her for who she is. The cheeky,compassionate, sweet and loving child. But her behaviour is so 'big' that some people find it hard to see past the behaviour to see 'her'. Some people will 'get' her, some people won't. That's just the way it is, you just have to do your best to work positively with the people who are caring for him, & hope they will do the same.