When I used to go up to London reasonably regularly, I’d (try to) pay the congestion charge in advance, before leaving town (I lived in Bournemouth at the time).
It was ridiculous. A lot of shops would say, ‘but we’re not in London, you can’t do that here’ - yes you can.
Some would just outright refuse and say they don’t do it without checking or looking at their pay point machine at all.
Others would try figure it out but then give up and say that they don’t provide that service - yes you do.
Eventually I found one shop that let me actually look at their pay point machine. I figured it out in seconds, it was very easy and pretty hard to cock up.
I imagine they’ve changed now - but the terminal had a one line LCD display, up, down, left, right keys and a keyboard. All you did was press up or down to scroll through all the companies and services until you got to ‘London Congestion Charge’, selected it, then it said, ‘enter vehicle reg’, you used the keyboard to enter the car reg and pressed enter, that was pretty much it.
After I’d shown them how to do it, I had to go to that particular shop every time - because I knew that they were the only ones who would actually let me pay the charge there.
I don’t understand how they can’t do it, or why they need extra training. It’s kind of pathetic.