I got ABBC (French, Maths, Biology, Chemistry respectively). My predictions are A*AAB and I'm applying to pharmacy this year with requirements of AAB-ABB.
I had a real struggle for my maths teacher to predict me an A eventhough I had a solid B. My excuse was that my university offer depends on it (which is doesn't but I had to make myself seem desperate for that A), my school are too being very harsh with predicted grades. I think you need to talk with your teachers seriously and come up with 'excuses' e.g. my offer depends on this grade, it's my loss not yours if I don't get it, I know I can achieve it, I'll bring you my work every lesson to show you what extra things I've done etc etc.
What course are you applying to, and to what universities?
I know someone who got a low B at AS for maths who came to my school, and he begged and pleaded for an A because his universities also required AAB, they really did doubt his abilities but after giving it to him and him getting offers for pharmacy, he was really motivated, retook 2 maths exams and came out with an A* in maths.
So it is possible but you need to talk with your teachers and put the effort in yourself to actually get the grades I guess.