My Oyster card started playing up today. "Seek Assistance" is said in bright red text - no matter which ticket barrier I tried to use. Humpf! So I approached one of the (many) idling blue-uniformed station assistants at Green Park for help. "Ah, yes", he said with a smirk, "these annual Oysters have now got Pre-Pay on them too. Means you've strayed 'out of Zone' at some point and run up a £2.00 debit. You'll have to pay that before you can use it again. It's been happening to a lot of other people recently".
Odd, I've not been out of Zone 2 for ages (darling) and certainly not since last night. How come you are allowed to run up a bill on a travel card? Surely it should just refuse you?
Well it turns out (after a long queue and short explanation at the ticket office) that actually there's a fault on the billing system. For many monthly and annual Oyster card accounts the system has not only added the ability to Pre-Pay (in case you wanted to load up your card with credit prior to venturing 'out of Zone') but also added an illusory £2.00 debit just for kicks. Nice. So many of those other people the station assistant mentioned who thought they might have gone 'out of Zone' were actually being diddled by London Underground to the tune of £2.00 each.
I had a feeling LU couldn't be trusted with a billing system. Let's face it BT still get it wrong and they've been doing it for 50 years. My advice if it happens to you with your Oyster card - ask!