If they think the academic in question is qualified then that's probably (annoyingly!) a nonstarter. The feedback things is less than ideal. that could be an opening if your institution classes inefficient or inadequate supervision as a procedural issue. You should ask your Union about this, and take any evidence.
The personal circumstances thing is a possibly stronger opening, but it depends. The supervisor themselves do not have to (and should not) account for your personal issues or illnesses etc.
There are School-level mitigation procedures for this that apply outside of the supervisor. Indeed, it would be inappropriate in most cases for any supervisor to act outside of these procedures. However, if you tried to act on this and were not facilitated then there is an argument that there has been a procedural mistake, viz. that the relevant mitigation was not made available to you.
The big caveat here, though, is that the onus for seeking mitigation and getting in contact with the relevant people rests on the student and not the supervisor. Did you do this? If you did and it was ignored, there's maybe a route to challenge things. if you didn't, then I can't really see how a successful appeal could be mounted in the majority of cases.