I teach piano - here's my view if it helps...
Changing the exam board you use will not have the slightest effect on the problem your daughter is having.
Some of my students take exams and others don't. I use the ABRSM because it has worldwide recognition.
It isn't the board, it's how the exam system is being used.
Grades help in lots of ways if used well. The student has a goal, they get feedback and a nice certificate. They also recognise a certain standard of playing.... or they should!
Unfortunately you find (and this was the case with my first teacher) the exam syllabus being used as a teaching syllabus which is where you get problems.
I teach to a certain standard, then if we want to take an exam we look at that syllabus after the student has attained a decent enough level of sight reading and other skills to be able to enjoy learning the pieces at a reasonable speed rather than slogging through the same 3 pieces for a year or more.
Scales/aural ability etc... I teach as a natural progression according to key. some of the ABRSM scale requirements for certain grades seem a bit random. This is OK if students are already familiar with them all. If not, they end up trying to learn a load of seemingly unconnected scales and often aren't sure how they relate to the music etc...
Anyway, after a while of being presented with new grade books straight after the previous exam, it gets harder to learn the pieces as sight reading standard and other skills haven't reached that level.
The student is frustrated and feels they aren't making progress and it all becomes a big chore :(
I prefer to use grades as a formality - once they are at the standard then they look at the exam, that way they are over prepared.
It should be about enjoyment, although annoyingly, the better you get the more enjoyment you get out of it, so without progress it's difficult.
Aim for small goals and short practice sessions but ask the teacher what your daughter can best do to make the practice sessions more effective.
Ploughing through a piece from start to finish repeating the same mistakes isn't effective.
Going to a lesson should be about learning how to practise as that is where the bulk of learning will be done. Half an hour a week isn't enough in itself.