My GCSEs are 6 A*s, 3 As, 1B
My iGCSE in science is AB.
My AS levels were AABD
And my A level predictions are uncertain, but somewhere between AAA and A*A*A.
What I'm trying to say is I got two Bs in GCSE and a D at AS, and still managed to get a place - your grades are amazing so don't beat yourself up! The course is likely very oversubscribed, and perhaps your ps or reference weren't exactly what Durham was looking for.
That doesn't mean that you, or your grades, or ps, or reference aren't brilliant!