Yes. Because of the delays in getting a card., you are also prevented
from buying an annual ticket (and therefore further savings). The card is
encoded to only sell tickets with a discount if they expire before 30
September. Last year I didn't get my card until part way through October.
I asked to have the ticket backdated to start 1 October so it would allow
the discount (it worked out cheaper for me still), but was told it could
not be done.

Curious - I've purchased annual tickets at Stratford, Vauxhall and Russell
Square. Each time it was some days into October and so they sold me it at
an annual ticket price but running from that day until September 30th.
(And I always had the fares leaflet with me to check.)

[snip]

Try Russell Square or somewhere similarly near to a university campus.

Thanks. I will try there next time.