The idea that ECs have to deal with owner to owner bullying seems to go way beyond anything allowed for in the strata act. There are plenty of options available to individuals who want to protect themselves against bullying, not least of which is an Apprehended Violence Order.
However, if the bullying is by the EC or actively condoned by the EC, they may find that their EC Members’ Insurance coverage has just sailed out of the window – in which case they could be liable individually for any damages that might be awarded by a court.
But to answer the original question, the answer to being bullied is to collect evidence, get sworn supporting statements from friends and neighbours then threaten legal action (such as an AVO). But only make that threat if you are prepared to follow it through – the world is full of people threatening to sue each other when both sides know that’s not going to happen.
By the way, the EC should get involved if the bullying involves any breaches of by-laws such as the playing of loud music or abusive behaviour on common property. And perhaps that’s where the duty of care comes in. But it’s primarily about the by-law breach, not the intent.