School won't give ds2 classroom support that he has been allocated!

[laura4jasmine]

We live in Scotland and my ds2 is 4yo and in nursery attached to primary school. Last term he was assessed for classroom support and had a IEP created. I was thrilled to be told that (apparently, unusually) he was allocated support in nursery for this year. I was told it was usually started in P1 but since we already knew his needs, he should get the support sooner. Anyway, there is a new nursery teacher and assistant this year and I gave them some time to settle in before I started to question what was happening with his support. Finally found out today that even though the educational support officer had support agreed for ds2, the support for the whole school is given in a lump and it is the head teachers decission who gets the support. She has decided ds2 is getting any support. How is this right? What can I do about it? I'm just speechless that she can just, without any consequence, take away the support my son was assessed for and allocated.
I have a meeting arranged with the nursery teacher for Mon to get the schools full version of the situation, I also have the educational support officer coming to see me on Wed but I'd like to be a bit prepared on where I stand. Please help if you can, any advice would be REALLY welcome.