DH has been off work sick for a while with stress and anxiety and has raised a grievance relating to health and safety issues. He has a lot of evidence etc, the whole thing has gone on for years.
He's named his main boss in the grievance and has mainly been dealing with HR and the managers that have been nominated to investigate. Today, DH's boss has tried to telephone him twice and has left a message saying he will ring again tomorrow. Is this allowed? Is DH obligated to ring him back?