I've had 'em
When I was a young working man, and pretty much every hour was given to earning a crust so I could afford my flat, I had cut back on all my costs and outgoings, such as the TV licence.
I sent them back their letter, explaining I don't watch TV.
One day, I got a knock at the door and two of them were there asking to see my TV. No problems, as it was all legit. They came in, checked the back of the telly for an aerial or cable to the wall socket of which there was none, as I'd got rid of it to avoid that trap.
Then they went through every single channel - none of which had ever been tuned into the frequencies for any of the channels.
Whilst they were doing this, they were asking about the PC setup I had in the living room as I had lots of machines running as servers and bits and bobs lying all over the place. One of the guys told me his sons PC had a virus which kept shutting his PC down after about a minute. I gave him written instructions on what to do and he ticked a box on his sheet and said I'd never hear from them again.
To this day, I've never watched live broadcast TV or any BBC streaming service which means I've saved somewhere over £2,300. When you look at it that way, that's not a small sum.