In message , at 11:59:34 on Thu,
18 Sep 2014, Mike Bristow remarked:

I think they've only ever issued cash refunds via customer services.

I've recently had an oyster refunded at a ticket office, so they
can do it. It was refunded onto a card, rather than cash.

That's traceable, in event of fraud.

Perhaps there's a floor limit for genuine cash refunds?

Later, from TfL:

"Refunds of pay as you go credit can be processed at Tube station
ticket offices. You will need to provide proof of your name and
address for refunds over £15.

"To get a refund at a Tube station ticket office, you must bring the
debit or credit card that you used to buy the tickets or pay as you
go credit. The maximum cash refund value at a Tube station ticket
office is £250."
--
Roland Perry