[Question] suing my high school?



Some background information: Im an Australian girl studying at a British school in Saudi Arabia and I am currently in my senior year of high school. If anyone is unfamiliar with the system basically, I am doing "A-Levels" and most universities require 3 full A levels (Year 12 and 13 put together) In year 12 you do AS subjects (half an A level) and then go on to do A2 Subjects in year 13.

Basically I am taking Art, Sociology and Geography. When I started school this year I found out i didn't get the best grade in Geography however i wanted to repeat a unit and carry on to A2 which i should have been able to do as i knew previous students who did worse and could do it and i emailed my old geography teacher and he said there wasn't any reason that i couldn't do it, as long as i was resitting my old exam. When I came in they told me i was unable to do it due to there not being a teacher for about a month and because im the only student wanting to take A2 geography they said there was no point in teaching only one student so they forced me to take up another AS subject instead.
Its been a month and a half and it turns out the geography teacher isn't coming at all, now I've found out that there is no sociology teacher coming either and for the past month i have been teaching it myself. My parents emailed the principle but he blamed it on me not getting a good grade and that a substitute teacher would do sociology, it turns out the new sub is the old sociology teacher (the one before my previous teacher) and she was told to stop teaching it as everyone in her class was getting really bad grades. Id also like to add that this is a very expensive private school.

so i was wondering if its possible to sue my school? or does that sound kinda stupid? how would i go about that? its a little harder as i am in saudi arabia so i am unsure
sorry for the long explanation, i would appreciate any advice