Well, in theory, the Oyster/contactless system works well. I flash my watch and all is mostly good. Sometimes the fare calculations are baffling but are generally less than I'd pay on a paper ticket from the station (at least I still have the option of paying cash, I suppose). I travel a lot for work (which I can put on my mothership Amex) and now I got to the mothership two or three days a week which isn't enough to justify a full travelcard.
I assume in this case that whatever Southern use to detect a card or device has been touched-in didn't tally with the actual card or device that I had used, despite it being the same thing. Since I've had my card checked before, that's generally worked fine, so something to do with cards on devices, I guess. It's a shame, because Apple/Android Pay on devices is quite sweet, it was only going to be a matter of time until I fumbled my debit card down the side of an escalator in the morning crush or lost my phone to the station stampede.
And honestly, it'd be fine if the recognised the fact that technology could be at fault, that I'm not habitually dodging fares, and provide a simple method where I can call them and say 'erm, I think you have this wrong,' at which point they'll see I'm touched-in at the time Southern say I'm not. The third time you're redirected to a 'thanks for calling TfL' message, well, you get a mite tetchy. Especially when they assure you that 'yes, there will be actual human.' I don't want to guy being the dick to low paid call centre operatives who have no more power than I do, and can only follow the script. Which is why I gave up and filled in the bloody online form. And no, I don't want to contact them via Facebook or Twitter. How about a fucking email, the same mechanism as you contacted me? And also that there's no checks-and-balances, TfL know when I'm travelling, they have the data of where and when I touch in and touch out.
(Weirdly, they've charged me a odd maximum fare of £5.40, which I don't think is the daily cap and presumably for the single journey I actually took from Victoria to zone 6, also ignoring all the other travel I'd made that day.)
I think the TOCs were pretty resistant and obstructive about the entire Oyster thing – I still don't think train stations will have anything to do with it, other than via the ticket machines (jam-filled babbage engines, in other words).