I bank with Nationwide and also have internet banking and a credit card. Each week I take the transactions off the internet banking list of transactions for the credit card and feed them into a program I have written, so that I have an overall idea of our finances. Occasionally, the balance on my program does not tally with the internet banking: sometimes this is due to a typing error when I typed in the amount or even a transaction that I missed and failed to type in, but lately I have discovered that Nationwide are sneaking payments into earlier dates. For example, on the 20 AUG they might sneak in an extra transaction for 16 JUL. Usually this is due to refunds from shops (when the wife takes things back) and it frustrates the hell out of me tracking down the discrepancies.
Today, however, I discovered that even the paper statements that they send through the post to me don't tally with their online banking. So I've told them they're getting no further payments from me until they can explain what they think they're playing at.