I've nc for this.
At my DC's school children were asked to choose their 5 Highers. We were specifically told that it was extremely unlikely that they would not get the 5 Highers they asked for. But just in case, they were asked to put down 2 reserve choices. We were again specifically told that in the very unlikely event that the school was not able to agree to all 5 Higher choices, they would contact us to discuss what to do, before allocating one of the reserve options.
They sent out the list of Highers allocated to all the children, having already finalised the timetable. My DC was allocated 4 of his choices, but was not given a 5th higher. The one left out was the one that he is most keen to do, and has based his university and career plans around. They did not contact us to discuss, and have not allocated him a 5th higher from one of his reserve choices (or at all).
When DC wrote to the school to point out the mistake, they told him that they could not re-arrange the timetable.
DC is strong academically, but as far as the school is concerned he will now be taking 4 Highers only. And not the subject that he wants to study at university and that he will need for his planned career. He had already told the school that he wanted to study that subject for Advanced Highers. He doesn't want to do the Higher in S6, as he plans to do it at Advanced Higher level and may possibly want to apply to Oxford or Cambridge, which would in any event require an Advanced Higher in the subject.
I have written a letter to the school, asking them to come up with a solution. Any advice would be welcome. I think it unlikely that any other accessible school would be able to accommodate DC's choices at this stage, and of course he would be very unwilling to move school (he is doing very well at the current school and is settled there) and a move would probably mean serious transport, time and expenses issues.