Chris Tolley wrote:
Roland Perry wrote:

In message
, at
14:11:42 on Sun, 8 Aug 2010, CJB remarked:
TfL explained that it could not be aware of any over-charging until
the issue was reported by a passenger.
Apart, of course, from looking for cards where there were two top-up
[bank charges] on the same day.

Yes - some passengers will do that, but that doesn't actually matter.
What you are looking for is top-ups where there were two debits but only
one amount of credit added.

Not holding an Oyster card, I wouldn't know, but in many cases the
financial part of e-transactions is handled separately for security
reasons. If that is the case here, then how would TfL know in detail

TfL would need to reconcile payments taken against the sale. Their
finance department would be able to run reports from their bank for all
card payments. I see no reason why each and every sale made via a
machine generates a unique reference number which in turn is transmitted
to the bank. From their they could pin-point any discrepancies between
bank reports and sale reports from each machine.

--
Phil Richards, London, UK
3,600+ railway photos since 1980 at:
http://europeanrail.fotopic.net
http://britishrail.fotopic.net