sweek wrote:

They do not, but you will have to reactivate them if you do not use one
for 2 years.

"The money on your Oyster card never expires - it stays there until you
use it.
However, if your card is not used for 2 years, you will have to
reactivate it or
claim back any unused cash by calling the Oyster helpline on 0845 330
9876. "

http://www.tfl.gov.uk/tfl/fares-tick...user-guide.pdf


Maybe that's what went wrong with mine? Maybe it just went dormant
before its time? I'd only used it two or three times in those two
years, and maybe that wasn't enough to keep it active?