Hi all, I have recently got my sac back and I think I have been unfairly marked

I lost 8 marks (20% of the sac) from super silly mistakes and have only managed to get 1 consequential mark.
I want to see if you guys believe I have been fairly marked and whether I should try to get my sac remarked by another teacher and how I should go about getting it remarked?
1st question (2 marks) received 0/2
Simple anti diff question: had to anti diff it then sub in like (1,3) to find c
I accidentally simplified x^4/4+12/3x^3+2x as x^4+3x^3+2x instead of x^4+4x^3+2x
I subbed (1,3) correct but in x^4+3x^3+2x
2nd question 2 parts (4marks total) received 1/4
i) had to find the tangent of x^2-7 at like (2,5) i cant remember exactly
i screwed up and diffed the equation by reading the 7 as a 2 and left it as 2x-2
subbed in all the other stuff correctly but for the equation 2x-2
ii) had to find the normal of the above equation
did all the correct working but for the equation 2x-2 (received 1 consequential mark for finding the gradient of the normal)
3rd question (3 marks) received 0/3
Had to find the maximum volume of a tray
Correct answer:
V=x(40-2x)(50-2x)
expand, diff, make it = 0 to find x then find volume
I did all the right working but I accidentally wrote V=x(40-x)(50-x)