College Problems - Need Help

My college professor told us on the first day of class that attendance was optional. The class is very simple so I decided no not attend the second day, at which they announced the class actually was attendance mandatory. I did not know this until over a month into missing classes. Now, the class ended early, and having a higher attendance score would push me from a B to an A. The professor refused to change the grade, should I escalate into a formal appeal or is there another process I should try first.