My wife was involved in a problem with her senior manager.
Her union rep was well meaning, but timid & unassertive,
verging on ineffectual.
He was more wrapped up in his own family concerns
causing him to cancel and rearrange meetings
and drag things out for weeks longer than necessary.

Not the best represetative, but the only one available in difficult circumstances.

Still, the underlying principle remains is it is essential to respect
the right to union membership.

My wife eventually came out of the dispute reasonably ok.
But a stronger union rep may have secured her a more positive resolution
requiring the manager to publicly apologise
and accept personal responsibility & blame for creating the problems
in the first place.

Then again, that hypothetical outcome may have resulted in a Boss with a bruised ego
and hostile grudge against my wife
and who knows what vindictive disputes further down the line ....????