hello earthtomummy, this is an all too familiar story, sadly.
We have been through several years of our child not being properly supported in school, but made to feel responsible for the outcomes of his clear signals that he cannot cope.
We spoke to a parent liaison advisor at the LEA, who advised us to put any concerns in writing to the headteacher, and to ensure that we copied in the Chairman of the Governors.
She said that all too commonly the governors don't put pressure on the head to fulfill support for children who need it because they are (or claim to be), unaware of the situation.
She also advised us to copy the school SENCO in on the letters, but as this was the headteacher at our son's school, this didn't really help.
It is also worth finding out who the governor with responsibility for SEN is, and having an informal chat - catch them at the school gates, or phone them up. Hopefully they will be determined and dilligent - providing you with a source of support.
(Ours wasn't, but got so upset at her inability to help us and other families that she took her children out of the school and moved elsewhere!)
As usual, you will have to walk that fine line between trying to get the best support for your child, and annoying the teachers.
I am amazed at how diplomatic I could be when all I really wanted to do was rant!
I wish you the best of luck with this situation.