HPaaS
I signed up for HP'sr free-ink-for-a-year offer. The way the service works is that they monitor your printer/cartridge status remotely (the printer calls into HP).
When the HP-supplied cartridge developed a fault, the printer stopped working and because I was unable to print further, no further cartridges were sent ;-/
Then (I wasn't paying attention) the free first year expired and HP began to charge me for keeping their useless printer in my house. Zero utility. And when I cancelled (rather angrily I'll admit) they insisted that the contract I'd signed took some time to cancel and then charged me an additional month.
Never again, HP. I'm with the others on this list, bring back the LJ4 mono please - the original version and not some stripped back shite.