Brother had exam board change in last week before exam - Anything we can do?

Hi,
My brother was intended to resit his GCSE English Lang/Lit this May; He was told he wouldn't be entered into the November exam.

He was. Furthermore, he was only notified of this a week before the exam. He was also entered under a different exam board to the one he has studied for the last few years, and so he had to miss some questions as he wasn't taught those texts before.

Is there anything we can do to rectify this? I'm unsure what we can do against the exam centre, but obviously this has severely impaired his chances of passing the exam. This is really concerning, and I'm not sure what should be our family's next course of action, if we can even do anything except resit again.

PS. Never go to a school in the Chichester College Group. They are horrendous, and they've had incidents like this on repeat for different schools throughout the group, for different students. Maybe the worst schools in the South-East.

First of all, are there any more exams for this November or have they finished now?
Second, keep and save any communications from the school about the entries. You say "he was told he wouldn't be entered" - was this in writing?
Third, is this at a sixth form / college he currently attends or is this sat as a private candidate at a school he used to or has never attended?

I'm unsure if there are any more exams, but I believe so. He's sitting all 4 English GCSE papers.
I'll check with him about whether this was said in writing that he wouldn't be entered
This is at a college he currently attends, and he is not a private candidate