This year, as we all know there have been so many mistakes in exams (I sat one of them) which in themselves are totally unacceptable.
But then there are so many mistakes in even the marking of exams:
A paper I sat and got given a U for (29/90) got sent back for a clerical remark (as in to check if they added the numbers up right). It came back as over 90% or A* equivalent. The content wasn't even remarked - it was just the wrong number had been given.
How are exam boards still allowed to function in their current system? This luckily didn't cost my a university place, but it could have!