It is an unfortunate consequence of a civilised society that nasty individuals can engage in nasty behaviour without fear of having their faces smashed in. It does not help when some seem to excuse the bullying and/or blame the victims, which optimises society for bullies, so you end up with nasty/vindictive at the top of the heirachy. This is why in some cultures, the tradition is to solve problems like this yourself by whatever means you think necessary, which doesn't always work out well for the bully.
The only thing you can do if you don't have power and authority yourself is to get power and authority on your side. Otherwise you are a slave to the bully and they know it.