Freda needs to consider her ability or desire to manage a team. If she would like to keep the job, but is feeling unsupported by her employer, she should ask for a meeting and request some management training. Its often the case that a good worker is promoted to a management role after a period of time, but is not equipped with the skills to do it.
Has Freda had an appraisal recently? If not she might suggest she has one.
Otherwise perhaps she'd prefer to request a reshuffle and a see if she can change back to her original role.
There are ways through this which should work for both parties, but at the moment there is no plan except unhappiness. I don't think its a grievance situation but if Freda disagrees a nd thinks it is, then she should submit one in writing with a specific complaint.