Decades ago I used to run a petrol station. The thin end of the infuriating customer wedge were the ones who would fill up to the point the pump would cut out, then withdraw the nozzle and attempt to squeeze another 0.1L in. Of course, this renders the auto-cut off useless, so once in a while it would result in a customer covering themselves in petrol/diesel through their own stupidity
"Your pump is broken!!!"
No, your brain is broken.
The worst were the ones who would fill up, drive off, then appear a day or two later. "You sold me dodgy petrol, your tank must be full of shit! I broke down minutes after filling up!"
Yes, that's right. Of the hundreds of people who filled from that tank either side of you, you are literally the only one who has come back in here complaining, which means there absolutely must be a problem with our petrol and not your car. I mean, every morning I go out and lift the manhole cover, open the filler, and shove as much dirt, gravel, water, and anything else I have lying around down there just to make sure your car gets wrecked. I'm not happy unless there is a queue of broken down cars and irate drivers lining the street by lunchtime.
By far the worst though were the ones who burst in ranting and raving at completely blameless staff. "Get me the fucking manager!". So I would go out and tell them to calm down and stop abusing my staff. "You can't speak to me like that!". I think you'll find I can, and I just have, and what's more, do not bother coming back here, your custom is not welcome and you will be refused service. "You can't do that!!!". Wanna bet? "I'll right to head office!" Good luck with that, this place is privately owned and I set the polices. Now off you fuck. Have a nice day!