This morning I traveled to work from Syon Lane station to Putney as usual. I always use Oyster card and always have a valid ticket but this time over the weekend I forgot I dont have enough credit. I only had £1.20. So I was about to use the ticket machine in the station, but it didnt take notes and there was a coin stuck in it so basically I couldnt pay by cash. I couldnt use my debit card because I didnt have any balance left. As I arrived in Putney I explained my situation but they still made me pay £20. I would like to appeal this as I think it is unreasonable to make me pay penalty because the ticket machine wasnt fully working. (There is no PTT machine in Syon Lane as far as I know) I would appreciate any advice on this.