a SCHOOL excused absence) I would go straight to the principal and AD director.

My son had a jazz band teacher who hated that he would miss class for his sport becuase he was the pianist. He would give him a "0" with nothing he could do to make it up. My son sent him an email and he said it didn't matter. I sent the teacher an email and CC'ed the principal and the AD and his grade was fixed in an hour. School excused absences were never a problem after that. My son was a sophomore and did not do band ever again though which was a bummer.