Fighting back, documenting and contacting the union usually doesnt work the first time but each time theres another incidence of something that could be considered inappropriate behavior the pressure mounts in your favor.

HR is there to protect the company, but once you can show a pattern HR is there to protect the company Once the cost of you potentially suing for them failing in their duty of care to protect you from workplace bullying and harassment is more than the cost of replacing the assholes doing it then they will act.