I don't like the way that Gio has been thrown under the bus with these accusations. There's no proof either way - just lots of hearsay.
I think he's possibly a very hard taskmaster - but he was also great with Debbie as she was grieving, and he was also great with Rose. I don't think he's the pro you would give to someone who needs a little more love and affection, and calmness (e.g. Johannes and Annnabel, or Gorka and Katie Piper) but that doesn't make him a bad pro or bad teacher.
I suspect that it could be a few things
a) a general personality clash (I don't think AA comes across as the most easy-going of people)
b) perhaps AA wanted to return for the final, but the Beeb said no, so maybe there's a payment issue there - or she thinks she's entitled to x but because she walked, she's only entitled to y - who knows!
But I personally think that this is the most likely explanation
c) AA has been open about mental health issues. I suspect the relentless trolling she faced from the very beginning may have seriously affected her, and I don't blame her. In which case, perhaps she's making a claim for duty of care from the BBC (Layton could also have a case here) to protect her from harm. Perhaps it was similar to Will Young in terms of panic attacks, and that's what she wants footage of, to show that she was being affected by it.
Ultimately, no one knows - but the way the press and literally trying to destroy Giovanni's career seems horrendous.