My school is saying we cant give our exams(M25) can they do that?

so for context no one was coming to school a lot so they came up with this rule in mid year that you need to have 85% plus attendance to give the exams, now a month or so before the highest attendance is 68% and they are saying they will stop us from giving the exams. Can they do that? we already paid the registration fees and everything, so can they stop us?