How to deal with dramatic drop in grade due to strict attendance policy
You do not currently hold a 91%. You may have held a 91% percent yesterday, but now you hold a 76%.


  Am I wrong to feel as though this is an unfair mark?


Given that you knew the policy in advance and the teacher seems to have been consistent in taking attendance, you seem to have no logical reason to feel the mark is unfair.

You state that attendance is a "small reason", but for whatever reason the teacher feels is is a big reason (15% to be exact). If you felt that the grading policy was unfair, you should have discussed this at the beginning of the semester, not after missing 3 classes.

Realistically, the only thing you can do now is beg (aka grade grub). Your mileage may vary, but most professors do not look kindly on grade grubbing. It is important to realize that to an outside, the policy seems fair. For example, in a typical US semesters of around 17 weeks each class accounts for between 1-2% of the taught material. Further, missing a class likely means you are not at the right point in further classes so each absence is like missing 2-4% of taught material. That sets a minimum of 6-12% of missed material for 3 absences. Multiple absences probably means you have missed even more material. In other words, without knowing the specifics of the class, a penalty of 15% for 3 absences seems reasonable.