sbb.ch definitely will sell you a ticket to Lörrach. I just tried it - 9CHF single Basel SBB->Lörrach
https://www.tnw.ch/assets/files/cont..._Juni-2018.pdf
(Sorry, it’s only in German)
Basically if you buy a 2 zone ticket from Basel Centre that’s good to St Louis or Weil.
The supermarkets have a much bigger range of products, there is no queue at the border (for getting stamps at the customs).
Tram No.3 or Bus 604 will get you to the st.louis station.
If you got a GA, you only need an additional Ticket (sold at the green TNW Machines) for 1.90 sfr one way.
There is one at SBB at the 1st platform.
You can get a 4-times stamp ticket for 10-12€ I think (don't recall exactly).
A 6-times multi ticket has a 10% discount.
https://www.tnw.ch/assets/files/cont..._Juni-2018.pdf
https://data.lenaxis.ch/wordpress/wp...riregio_FR.pdf
Tickets can be bought with the BLT app
If you go often use the multi pass. It is AFAIK valid in both directions. But you can mail them once more.
TNW 2 hour tickets are always only valid for one direction !!! No going back even if within the validity period !! No joke.
Allgemeinen Tarifbestimmungen TNW Tarif 651.0
https://www.tnw.ch/assets/files/cont...t-Anlage_1.pdf
This is a very big difference in contrast to example Zurich ZVV where a single 2h ticket is valid for any ride within the validity period. Forth and back as much as you like. ZVV-Verbundtarifes, Tarif 651.8. Section 1.03 https://www.zvv.ch/zvv/de/abos-und-t...sbereiche.html
Don't go to the SBB counter because they will charge you almost double the price for the exact same train (line S6).
Go to the German ticket machine (on Platform 1/2 I believe) and buy your ticket(s) there.
Look for 4-time stamp card for additional savings (10-12€, don't recall).
This ticket is valid for the entire RVL (in winter time you can reach all the way to Feldberg ski area for just a few Euros).
Stamp one in one direction, another when you come back - total cost probably 5-6€.
I suggest you go to their SBB counter and ask for a ticket to Feldberg (or Zell im Wiesental, where the S6 stops and one needs to switch to the bus).
And share your results here.
From my firsthand experience I can tell you they do not direct you to the RVL machine, where you get it for far less money.
Does it mean I can sue them?
P.S. In your earlier post you yourself state that SBB app tells you that the Lorrach ticket costs 9CHF.
How does that align with what you are contradicting me for?