Thanks for the flashbacks, el Reg
the time he was despatched from his UK home to an African nation, where his client operated both a mining company and the national airline.
An unstable African nation (pick one) had a certain government agency "forget" to pay their internet bill. This made the ISP (a multinational) rather upset, so they sent out an expendable *cough* junior tech who "looked the part" to do support on site. And also, to get the customer to pay its' (huge) overdue bill.
When I say he looked the part, the criteria was essentially "Joe is black, he's less likely to get shot, so send him". That may or may not have been true, but "less" did not mean "zero", a fact not lost on Joe.
Joe cleaned up a lot of the bad processes and discovered that the nonpaying customer was not only paying them (or not paying them) for internet access, but also VOIP. So, when they refused to pay for the third time, he pulled the plug on the agency, disconnecting all of their phones.
Unknown to Joe, the agency was the parent agency of an "off the books" security agency. He was told this 5 minutes after he pulled the plug, by terrified local co-workers who realized what Joe had done, as they were fleeing the building before the pissed off Black Ops soldiers arrived.
Sure enough, ten minutes later, about 20 Toyota Technicals arrived at the ISP building, and it was soon surrounded by a hundred armed guys with fatigues, AK-47s, and black sunglasses, as the immaculately dressed leader calmly entered the building with a dozen of his crack troops.
They went into the head office, where Joe was sitting behind the desk. The leader lit a cigar, placed his AK-47 on the desk, and calmly said "I am here to ask why you have disconnected all of my troops' telephones".
Oddly enough, the meeting was strangely uneventful, and even cordial, as Joe explained how much was owed, and how, if he couldn't get some of the money owed back, the head office would simply pull the plug and cut off the entire country.
He was successfully able to get about 30% of the bill paid, and also not get shot in the process. That may not register in the company's financials, but Joe certainly appreciated it.
When the money transfer was confirmed, he turned the phones back on, and the soldiers left. So did Joe, the next day, to non-African pastures.
When he returned, he wasn't exactly covered in glory by his bosses. His direct manager wasn't impressed with the 30% payment he had negotiated, but begrudgingly told him that "you earned your ticket home", apparently thinking that was an option the company could choose to ignore rather than a requirement.
Reading the writing on the wall, Joe quit six weeks later. While the execs were not impressed with the 30% payment he had negotiated, it was 30% more than anything else they got in the future.