I'd also like to see some fare related options in the Journey Planner.
Especially a "Travelcard only" option to exclude the HEX etc. Also a
"PAYG only" option would be nice.

I'd just use the standard TfL contact page via this link
https://www.tfl.gov.uk/tfl/contact/default.asp?type=tfl

Yes, I've done this, but they did not react (yet).

Martin