Thetrainline.com is an online ticket selling company. You book tickets online, collect them from a machine at the station, and go on your way. The online system gave me a cheapter option than I'd managed to find searching through the touch-screen gui, so I thought I'd try to use it. However...
They don't let you collect tickets in Cambridge. They take 2 hours (!) to transfer the information from their database to the machines. They charge 10 pounds for cancellation, even if you never collected the tickets. So, when I ordered tickets in the evening in London before going home, I was totally screwed. I've been charged 10 quid to have a couple of lines entered into a database and removed a while later.
Mysteriously enough, while debiting my account was pretty instant, the refund process is insanely slow. For some reason, it involves phoning up a national rate number in order to cancel. That is, to cancel an online order. The website says it may be possible to change the ticket type. Nope, not a chance, despite the fact that no tickets had been issued.
My only possible interpretation is that the service is deliberately crap, and they plan to make their profit using refund charges from disgusted customers. Well, they got me. Bastards. I should have used a credit card for the order, and cancelled the item through that.