Aaah yes. A while back I rented a car in England, did a bunch of driving, and on my way back to the airport crossed the Dartford Bridge in the dark. For some reason you have 24 hours to pay it then it steadily becomes more and more impossible. I wasn't able to get online to pay it and flew out in the morning. Que a year of increasingly ridiculous demand letters from whoever runs that tolling system. They escalated to sending me bills in the US with short windows to pay which of course arrived after their demand window closed. So I never paid it.