Sorry for the "old guy rambling on post", but hey, I can't help myself. 
My "worst" experience, from a head-banging point of view, was about 12-14 years ago. I was asked to format a HDD, seems the woman's(my aunt's co-worker) hubby had pooched her new system, BSOD's, couldn't connect to the internet, and so on. I lived in Larder Lake, 18 miles from Kirkland Lake, where they bought the computer, and they lived 12 miles past there. I was offered $100 and all the beer I could drink
(makes a fella wonder how the computer got pooched in the first place, heh), so, colour me there.
I got my aunt to drive me out, I knew I wouldn't be driving back, I'd be looped, and got down to business. They had '98 as their OS(way before '98SE) so I asked for the disks. She gives me the CD(I brought my own format disk), which is burned, and it's written on it, in marker, Win98. I ask her where the original CD is, the one that came with the computer. She tells me that's all they gave her, an obvious rip off. So whatever, the shop robbed her, I'll use the burned copy.
...I backup all her important stuff, then format. Boot from the floppy, go to the CDROM, and hey, "setup" doesn't work. I try "install", doesn't work. I check the CD's directory, yeah, I got a recovery CD for Win98, nothing else on it. Now I'm peakin, my aunt bought her computer from the same shop, I figure she got screwed for the '98 CD too. My aunt tells me to relax, she knows the guy at the store very well, she'll run in and get the CD, says I should have a beer and relax, she'll be right back, and off she goes.
Have a beer and relax, yeah, okay. Let me tell you about this place. They lived in Tarzwell, which is the equivalent Buttfug, Idaho, only there were more weird people in Tarzwell, even though the population was like 50 people. Not counting sheep. She worked for the Gov't of Canada, he collected welfare from the Gov't of Canada, and drank beer. Nice work, if you can get it. They had this dog, a Heinz57, that was in heat, it was dripping blood everywhere, which explains why they told me to leave my boots on when I first got there. This was in March, lots of snow, I was curious at first, but figured it out as I watched welfare-boy chase the dog around the house with paper-towels, wiping up the blood. I decided to move to the couch to drink my beer while I waited, welfare-boy pipes up, tells me to wait a second while he gets a towel, the dog has bled all over the couch. I say forget it, I'll just sit in the computer chair. The drywall isn't finished, maybe they're renovating, I don't ask, but 1/2 the walls have the board up, the rest are insulation with poly over top, stapled on, impressive. I use the can, well, seems the old door was a 36" exterior door, and they bought a 32" door. The old door framing(RSO) was 38". I go to hang a rat, close the door, and look out into the livingroom, because there is a 3" gap on both sides of the door, and it hasn't been filled in with 2X4, nor had drywall on it. Nice, welfare-boy's fat wife can watch me pee.
Two beer later, my aunt returns, she tells me that buddy at the computer shop where they bought their system says that they don't get the full '98 CD, so we'll have to bring the system in to have it installed. I lose it. She has the freakin OEM manual, with the "To be sold with a new system only" sticker on it, and she doesn't have the CD, just a recovery disk. Buddy is scamming, he's selling the OEM CD's, and just shipping recovery disks with the systems, I figure it's time to rip him a new *******. I grab a couple "roadies" for myself, and get my aunt to drive me back into KL.
We get to the shop, I'm loaded for bear, I figure I got some guy my age to have a go at, he's getting a piece of my mind(what I can spare), and I'm not leaving without the Win98CD for Heidi, and another for my aunt. We get to the shop, and walk in, I see this older guy, maybe 55, talking to a customer. My aunt tells me he's the guy. Now I have to make a judgement call. Here's an older guy, business owner, talking to a customer, should I be diplomatic and call him off to the side, or should I just lay into him? I decide to use "Brundle Diplomacy". He looks over at us, says hi to my aunt, and asks who I am. I tell him I'm Goldie's nephew, then my exact question was:
Who the f*** do you think you are, do you think you can keep ripping people off for the Windows that they've already paid for? Just so you can sell them again? You piece of s***!
The "potential" customer he was talking to, shoots him a dirty look. He pulls me off to the side to "discuss the issue". Man, I got the calculator goin in my head, I left home at 10:30am, got to Heidi's at 11. Should have been an hour to backup/format/install, then the rest was beer drinking time. Maybe two hours, counting travelling time, I'm making $50 an hour. Instead, it's 1:30, I haven't got '98 installed yet cause I don't have the CD, and I see my "per hour" wage slipping downwards, very quickly. I have absolutely no compassion for this unethical SOB, so he gets the full "wrath of Brundle".
As he walks into the back of the store to get me the "TWO" CD's, his "potential" customer walks over and pats me on the arm, a nice older lady, maybe 55, and then says; "Thank you." I got back to Heidi's(welfare-boy drank 6 beer while I was gone, that's less than an hour and a half), installed Win98, grabbed 4 roadies, and left with $150, Heidi dropped in an extra $50 for my trouble, and for getting them the CD that should've been shipped with the system in the first place.
I guess it wasn't all that bad, except from an aggravation point of view, but it sure got my shorts in a knot. Nothing has ever been close to pissing me off that much since. Glad I got it out of the way early.
