Yanbu!
I've worked in lots of Call Centres and the debt collection and complaints depts for banks and energy companies were the absolute pits. Sometimes quite amusing and shocking in equal measures, to listen to fully grown adults rant, rave, scream, threaten and verbally abuse me (including a few death threats :) ) but often it's just tiring and bloody rude.
I've always said that those customers should have a recording of the call sent to them so they can listen to themselves behaving like idiots - I know I'd be thoroughly embarrassed if it was me.
Sometimes people can't comprehend that we physically don't make the rules, we are bound to them by the company we work for and we're not telling them that they will be taken to court/cut off/ account suspended for the fun of it or just because we feel like it.
The worst for me is when you open a call from someone quite clearly pissed off - rightly or wrongly - and they won't, absolutely 100% refuse to complete DPA to continue the call or discuss anything. There's just no reasoning with them.
I won't put up with people talking to me like a piece of shit, I'm simply there to do a job, I don't mind upset, annoyed, getting a bit pissed off - we're all human and I'll do my best to help you but when it turns abusive, nasty and personal - quite frankly I've switched off when it crosses that line and want the customer escalated or off the phone - some companies allow us to hang up after 1 warning, some after 3, some fuckers not at all.
I never get arsey with call handlers when I make a call as a customer because I know exactly what it's like. I'm not an angel and one company in particular tested my patience to the limits (I'm glaring at you Talktalk) but I wasn't once nasty to the handler I simply took my business elsewhere.