Pay and display with random coins.

Yesterday, I tried to park my car. The Pay and Display machine said I could use may card, but I could not get it to work. You could put in coins. It did not give change: that makes sense - the machine would be simpler and more secure if all the money went one-way in to an armoured box. However, it wanted £1.30. I had nothing between £1 and £2 apart from a 5p piece. So, I put in £2. The annoying thing is I only get 1 hour's parking for my £2 even though I put in extra. The machine could have given me 92 minutes of parking at the same rate instead of 60 for my £2 with only a minor software change.

This does not mean buying parking by the minute. It makes sense to restrict the smallest purchase to (say) £1 so people do not try to get back in five minutes.