In message , at 12:00:51 on Mon, 23
Jan 2012, AJM remarked:
Apparently, you log on to your Oyster account the day before travel and
change nominated pick-up point station. The refund doesn't have an
expiry date apparently.

You've got a bit longer than a day to collect it, but the later you
nominate a station the less likely you are to change you plans I
suppose.
--
Roland Perry