Cutting A level courses a month in

Funding is down to each school. They make the decisions on viable class sizes and what they see as cost efficient use of resources. If they have the teacher, and the subjects cannot easily be subsituted, (you cannot swap Spanish for French for example) then I would expect them to go ahead and teach to less than 10. If they are very niche and not necessary subjects, (eg Law, Film studies) then there is wriggle room for the school.

Certainly worth a fact-finding conversation with the School.

Have people dropped out after the course began? I know people did when i did french A level. We dropped down to 6, but this was in the days when they could run a course with only 6. Awful for students if they can't. I'm not sure how the funding works

I would encourage you to see the school ASAP. Not your 16 year old. It’s absolutely appalling. So are teachers leaving or couldn’t they count the number of students on these courses. My faith in the school would be shattered.

A school my friend's child went to they cut an option half way through since the only teacher who knew it left. The students then had to decide to self study (it was one module out of 6 for their A-level) or switch to a different module.

having to completely abandon a subject a month in will definitely disadvantage them. Some students may have chosen to take their A-levels elsewhere had they known this subject wouldn't be available and would have to start a new subject on the back foot. It's definitely recoverable but would be very annoying. I'd encourage your DD to set up a meeting to clarify ASAP.