The reason that exams are considered the be all end all is that they have the potential to scale your SACs, which depends not only on your performance but the performance of your peers. Yes, in most subjects exams are worth more than SACs, but it's the scaling that can act to help push someone's study score up. That being said, you can't bomb all your SACs, expect to smash the exam and get a 40+. HOWEVER, from your scores, you don't seem to have done as bad as you think, and I still firmly believe that a very good exam score can get you the score you want. If you can do really well on the exam then yes, theoretically, you can get a 40+. Without worrying too much about the technical side of things, trying your best from now will serve you well, since moderation is only partially in your control. What you can do now is work hard - I believe in you! - to do your best on the exam.
It's up to you where you want to focus your attention and how much time you want to spend on each subject, but I don't think you should give up now because there is still the possibility of doing well on the exam. I understand how demotivating a 'bad' SAC mark can be, but take it as a learning opportunity for the exam.