Most of us have had dealings with naff (rubbish) bosses, therefore some ideas / tips:
Get things in email or written. they will hedge their bets or avoid problems by speaking face to face or calling.
They (the bosses) will always side with the organisation… not the employee … you going is preferable then them getting into trouble.
Collect as much information about a situation as you can.
Speak to the union quickly, they will help you and are on your side. they know the law. the employer is scared of the law / union.
In some countries the union know the salary for your profession / age / experience etc.
Play the long game, you have more time and energy they need to multitask.
Choose which battles to fight … lies and gossip should be stopped but a day holiday here and there could be let slipped (not worth fighting over)
When you have something to trade, more work, need laptop. negotiate, otherwise you’ll get the least for the most work.
The bosses salary review should be done by those above (as normal) and below.