Think that is a joke, if you have the grades you should be able to enter any subject you wish. I had a huge problem for S5 course choices (subjects sitting this year) when the old guidance was trying to force me out to college with five 1's, a 3, INT2A and a fail in the prelims but I told her where to go and now doing 4 highers in fifth year.
I think guidance is a joke for not letting you do one more higher? This boy in my year got told to leave a week ago but his parents reported the school to the school board and is now being able to do 4 highers and a study with prelims results of:
Int 2 maths - 21% (n/a) he is able to take higher
Int 2 English - 44% (n/a) he is able to do higher
Int 2 computing - 40% (n/a) he is able to take higher.
Int 2 modern - 49% (D) he is able to take higher
Int 2 Art - 11% (n/a) he was offered to take higher.
If thats joke, I don't what is! So unfair on others told to leave!
Good luck with you choices!