To be honest, there is a limit to what you can do on sites such as these.
Some people get their kicks from moaning, complaining, criticising etc.
The moderators can only do so much, even if a posting is removed, it may have already been read by it's intended target.
Also, because the devs want feedback, an email address is often provided.
Another easy target for this type of person.
The only way to get rid of them is to spoil their enjoyment by not rising to the bait.
That's something we all need to do including the devs.