Without going into too much detail, a colleague has contacted their union because things are currently unbearable with one manager. They have asked him whether colleagues would like to fill out an anonymous collective bullying questionnaire.
I have no experience of union involvement and would like to be prepared for what happens next if possible.
The colleague in question has followed all the correct steps with raising informal complaints, then formal complaints, getting HR involved etc. Unfortunately, the person in question's behaviour is not improving.