How do they sleep?

I went to an old lady today to fit a door surround on her venerable Hotpoint 9530 about twenty years old on top of which was an equally aged 9310 drier both in good nick.
When I’d finished the job she said to me “do you know these people”-pointing to a sticker on the front of the washing machine. It was the boys from Sheffield (about 50 miles away)-I thought they’d given up years ago.

Their modus operandi:
Knock on the door
“We’re doing a free survey on your domestic appliances”
The guy walked in with his trolley and (I’m quoting the lady) scared her saying the machines could be dangerous etc.All she had to do was sign a piece of paper and he would take them away and sort them out.She asked him how much he said about £150.

The machines were returned and the bills were
Washing Machine £157
Tumble Drier £140
Vac £57
Theyd stung her for £350,she complained but paid up to avoid a fuss.Afterwards she tried trading standards but they said they’d never heard of them.
The lady said “it doesn’t give people in your trade a good name”-I had to agree.All I can say to these rogues if they come on this site-shame on you ripping old ladies off and for all the damage you do to honest traders(apologies to all the honest Sheffield traders)
Has anybody else come across this crew ?They seem to appear every few years under different but similar names and cause quite a lot of grief.