This is not the customer service of SBB, this is a public online forum where people in their free time help others. I can still help you:
Firstly, you can still buy a half-fare ticket at the ticket machine or online, just select reduced fare and you will get your ticket. Only the ticket controll staff will check if you have the half fare card. But you have to get a ticket in all cases!
For the half-fare-card, you have a few options:
- If you have linked your SwissPass to the app, you can also show the ticket inspector the app. There is a QR-Code on the app which they can scan and is equivalent to the physical card. Technically, you need an identification document together with the app, but this is rarely enforced.
- Go to a counter and ask for a reciept that you forgot your Swisspass. This will cost 5.- but you then will have a paper equivalent for the Swisspass vallid one day. This is only possible if you have an identification document with you.
If you don’t do either of those, and you are controlled, you should mention towards the ticket controller that you do not have your Swisspass with you. You will then have to present your SwissPass card to a railway counter within a few days and will only have to pay a very small fine (It happened to me once and I had to pay 5.-, but I think it is 10.- by now, not sure tough).