How do i convince them to change my last Semester Grades?

I got sick towards the end of semester one and missed 6 days of school.During those days I had classwork and presentations(worth 100 points) I missed.When i came back i asked if my teachers if i missed any and can i make it up because i was sick.(Notice they never ask me for a letter, even though that i was holding in it at the time i was asking them.)They told me that i should begin to write my portfolios letters and prepare for the midterms and regents taking place next week.So that exactly what i did.When the midterms came i did really poorly because it was hard for me to study.Now 4 mounths later i am looking back at my past grades and notice that they were not changed.I was suppose to be excused from the presentations i missed. I told one of teachers that my grades were not changed but she told me its too late and that she cant change the grades on transcript however two of my other teachers told me that it was possible to do so.





How should i approach this issue? I need my points back because my GPA too a dip(by 2 pts) that semester and those points will have a major impact on it.I am now halfway done with my second semester.How do i convince them to change my last Semester Grades?
See the teacher's boss.