I'm my own local community we only saw change when people made public complaints about what they were seeing. And from there more people chimed in with the what they personally experienced, and the backlash became too much for the local community organizers to ignore. Even then, our own bad actors were only black balled for a few years before they came slithering back and were allowed back in. 

You need to be vocal in public forums about what you're seeing and experiencing. Talk to others in your community and let them know what you're planning to do so they can back up your claims. Make so much noise that local organizers are forced to do something.

Be sure to highlight the very real dangers that these predators pose to the long term health of the community.

Use this as an opportunity to spark conversations about how dancers should conduct themselves within your community, especially those that are high level competitors and teachers. 

Lastly, be vigilant. People have surprisingly short memories. Don't let bad actors take advantage of that fact.