Submit an Academic Petition or Appeal

Petition Letter: My Econ 310 grade based on Onq grade would be A+, but my professor curves down my grade from A+ to A-. She told us curve down happens because the average is too high.
Based on my midterm mark(96),and final several assignment mark(almost all above or around 90), I know that I have high probability to get a A or A+ if I do not lose too many marks on my final exam and participation mark. So I spend more time on my other economic core course because there is no difference between 90 and 95 in my view and finally I receive 90.35 on term grade at least (5 participation mark does not show up on onq, I assume I receive 0 on that). As a student, I never worry about the possibility of curving down unless there is clear warning from professor. In fact, In the whole semester, the only information we receive about curving is one sentence in lecture 0, 'Numbers in, letters out But subject to scaling adjustment (e.g., if entire class's grades are too low)'. After that, we do not get any announcement until the final exam mark release and then curving down happens. Objectively speaking, professor could monitor all data of student's grade, if there is a trend that average would likely be too high, I feel making later assignment or test harder or marking more strictly or giving us new grading scale or noticing about curving down may happen would make me have no complain. All above method would help us realize that we are not good enough, we need to work harder to get a A+ . However, more than 5 curving down after final exam grades release gives us no space to improve us to get a a+. I receive that kind of curving without any notification before, which makes me think it is unfair. And as you know, third year and Fourth-year core class GPA are important for applying master. That huge curve on Econ 310 , the core class for all economic student, have decisive impact for everyone who want to appeal a master plan such as me.
Based on the reason above, could we get a more reasonable result about this curving down.I mail this to you instead of Professor Ye because I have mailed her 10 days ago with three mails but no reply, I afraid the 21 day deadline is coming, so I write this.