OP
i am trying to be genuine and kind to you here.
If you feel like you want to complain to the school read the policy or just email a complaint to the admin team. It doesn’t matter if anyone here agrees with that - do it if you need to.
Having said that, I don’t think you will get far - and here is why.
The head contacted you about today’s fight. That’s what she needed to discuss.
She may then have been concerned that you excused your son’s behaviour on the basis of his being bullied elsewhere but that’s a separate issue she probably knew nothing about!
If you want to raise the bullying towards your son you need to do that separately- to his teacher or to the head or both if you aren’t being listened to.
It seems a bit unfair to complain about the head if she didn’t know about whatever your son may be experiencing.
So break it down into small parts - dealing with the immediate fight between the children. Then address the bullying by speaking or writing to the teacher or head about the bullying.
Then, if you think you have cause to complain do so.
Thats what I’d do.
If you think of it like this - if you go shopping and the cashier gives you the wrong change and you complain about that to the manager would you expect the manager to also know that you also experienced a problem getting your trolley earlier that week that meant you lost the £1 in the trolley? Of course the manager wouldn’t know if you didn’t tell them and the two are related (because it’s the same store) but only vaguely.
A school head teacher is not going to be aware of every issue in every class or with every child.
Where you come in is that you raise the concern on behalf of your child being bullied and push for a resolution- but complaining about the head’s response is a bit premature because she didn’t know anything about the bullying and probably can’t see what it’s got to do with your children fighting.