On Mar 11, 3:00*pm, martin wrote:
Back at the start of January, to take advantage of being able to use
PAYG on National Rail - and to visit the steam museum there - I took a
trip from Wood Green to Kew Bridge.

The fares finder on the TfL site says that this should cost £3.10 off-
peak, or £2.05 with a Railcard.
I was charged £2.40, which is the z1-3 LU-only fare. This suggests to
me that either the fares finder is wrong, or the system is
overcharging.

For those who are still following, I finally got a sensible answer
from TfL:

I have spoken to our Fares and Ticketing department and they have informed
me that your combined National Rail and Tube journey should have been
charged £2.05 if you had a NR concession on your card.

The system as currently written does not give money back if the fare for the
journey up to the interchange is more than the fare for the whole journey..
In this case your NR discount did not register for your journey from Wood
Green to Vauxhall LU so the undiscounted TfL Off-peak fare (£2.40) was
charged for that part of the journey. Unfortunately the system did not
lower that fare for the rest of your journey.

Which makes some sort of sense, but I'd hope that this kind of thing
would be autocorrected. Perhaps it now is? My railcard has since
expired, so I can no longer check.

They've also offered me a £5 goodwill payment. Which was nice.

I still find it incredible that it's taken three months to get a
straight answer out of them. I think that probably deserves a letter
to someone at the GLA.