I put £10 into a ticket machine at P&O Ferries, run by PPS. When I returned to my car two days later there was a 'penalty notice' for £30, rising to £100 if not paid within a certain time. The ticket showed I had paid nothing.

I appealed against this and said the machine was faulty but they would not accept that, even though I sugested they would have £10 more in their cash box if I had paid. I later reluctantly paid them £20 and told them they already had the other £10. They then told me I owed them £80 (£100 less the £20 paid). I objected again. Now they have sent a bill for £107.50 to be paid by January 15th. Can they do this?

I have read some of your comments on car parking (in the Telegraph) and wonder if you have any thoughts on this one?

Incidentally, I later discovered that you can get a ticket to park free for two hours. I didn't check the ticket I had received for my £10. There is no parking office on this site. The people at P&O say they do receive some complaints from customers.