I was given a TFL Overground Penalty Fare Notice last Monday for quite a silly reason which goes: I'm tapping in at Clapton, on my way to Liverpool Street. It's 9AM Monday morning, and as expected rather busy. The Oyster machine tells me I haven't got enough money - negative balance - I'm waiting for the machine to free up. By now there's 2 minutes till the train comes, I'm on my way to a funeral and don't really have time to wait around. With around a minute to go, the machine is finally free, I see i have a negative balance of 40p and put in 40p to take it to 0 as that's all I have in coins and I don't want to break a note. I finish up and by now the trains already in the station, I tap in, run down the stairs and catch the train. When I get off at Liverpool Street, the barriers don't let me through; the guard has a look at my card on his machine and says I still have a negative balance and he's going to have to charge me a Penalty. I tell him everything, but he completely disregards it, almost as if I'm not even talking and hands me the notice. I check the online account a few hours later, and somehow the 40p I put in hasn't been registered and that's why I was charged. I've talked to a station guard and he says there's nothing more I can do about it and I should just pay the 40 quid and get on with it, surely there must be a appeal on the basis of check CCTV etc? The other thing I've noticed is on the ticket it says I travelled on the Liverpool Street - Chesunt line when it was the Liverpool Street - Chingford line - could I get off based on a technicality here? The Chesunt line dosen't even pass through Clapton. Is there a point in appealing or should I just pay the money? Thanks in advance for any help.