I work in the public sector in a regulatory body, but in the "back office" as the chancellor likes to describe us when deciding how much blood to squeeze from our budgets. A lot of complaints come across my desk for us to investigate as regulator, and sometimes there are people out there doing naughty things, but that can't possibly explain all the anger and bitterness that boils within the letters and emails that I see.
I've seen complaints from the same person that have gone on for years and years, re-hashing the same issues that just seem so minor from where I'm sitting, or that we've investigated time and time again and they always turn out to be unfounded. I know that it can be the little niggly things that build up over time, but without getting into specifics it's things like "so-and-so swore at me on the street/on Facebook", or "people keep parking in our cul de sac because of them", or someone quite legitimately wanting to set up a business next door, fully complying with all planning regulations and every other law going, but Mrs/Mr X doesn't like the idea. Fine you might not like the business, and maybe visitors to your road do make parking more difficult, and yes if they did swear at you that's not very nice (though the other party always claims they didn't), but really do these people expect an independent regulator to come along and take sides without any actual evidence?
More often than not "serial complainants" drag in the local authority, planning departments, the police, social services and every other agency they can think of as well to try to stop their neighbour/ex-partner/ex-friend from getting on with their life and their work, and it just makes me wonder how much public funding gets wasted and how many people are stressed and essentially harassed by the public sector on the behalf of their "frenemies". Plus it must just be completely knackering being that angry and bitter towards another human being. I know it's certainly knackering just reading all the ten page long complaint letters, complete with bolding, underlining and grauitious thesaurus usage.