In message , David
Cantrell writes
Or you just wait 'til the following day and go to the Oyster website
(assuming your card is registered) or phone the Helpdesk and they'll
sort it out for you with significantly less faffing around...

And that's what I did - or rather, I emailed them.

But the problem isn't that it's a pain to get a refund - given that you
can just email them and it'll get sorted out, it's *not* a pain.

Assuming they have a good record of sorting things out. My experience of
National Rail TOCs and their sorting out of compensation claims is that
you have to have a system to track every one.
--
Roland Perry