Martin Underwood wrote:

If the signs said that travelcards were not valid (which I think is what you
are saying) when in fact they were valid, then passenger were being wrongly
advised to buy the more expensive ticket. It's one thing not to advertise
and promote the cheaper ticket (though that's bad enough); it's another
thing entirely to give explicit information that cons people into buying a
more expensive ticket that they don't need.

As I recall, the Paddington PIS displays show the above note.
Presumably someone forgot to reprogram them.

It's a difficult one, really... I would suggest the best option would
be to make Travelcards valid on Heathrow Connect only, and not on HEx.
That way, the premium product could remain.

Neil