I thought (and if I get a chance can look into it tomorrow at work - I work in a bank - but not those 2 mentioned though) - that if its gone into someones account they would have to wait for that persons authorisation to debit it back out to reverse it back to you. I vaguely remember this happening a few years ago to one of our client's (though I wasn't involved in the case - just heard all about it through my collegues) and it seemed to take forever for that person to give the money back - I'm fairly sure it ended up being resolved - but it was a few months (thats why I kinda remember it cause it just went on and on forever).

Is the case actually closed? Or are they waiting for the person to respond?

If its not a valid account number then it should have automatically bounced back to you I would've thought...so I'm assuming it must've been someones account. I also thought that when you put the person/account name in the transfer it had to match the account number it was crediting (though I'm 100% sure on this - but I'm sure I've had clients get account names wrong and the money was returned - usually they've put a nickname instead of the proper name) - but I've only just returned back from too much time away - so sorry I can't be definite on this.

I would dispute it again as I'm sure you intend to. Call and speak to the internet banking section (as apposed to the branch) as they usually understand the internet banking system that little bit better (usually anyway so I have found).

Goodluck...hope you can get it sorted.