the 70+yr old Father in law was a victim of this. he got a "Support" phone call, "go to this site, install this software" etc etc, then when he asked them what they were doing, they got verbally abusive. he took a photo of the notepad window they had opened and the text they had typed. it was something nice like, "we now own your computer you <expeetive expleetive>, you kept asking questions so i'm going to <expletive> you" or something wonderful like that, from what I recall.
fortunately he had the presence of mind to take the photo and just hold down the power button.
It took his daughters naming and shaming talk talk on twitter before all of a sudden, his account was unlocked and password had been reset and he could access his account again as opposed to the hours of wasted time we'd spent previously on the phone trying to get him back into his account after this.
When his laptop landed on my desk it would load the windows7 kernel, and then a picture that looked like a computer icon from win3.1/9x popped up in the middle of the screen with "a password is required to start your computer".
did a full wipe and reload, god knows what crap they'd got installed on there. fortunately we had backups of anything important