Hey now, you have to read the details in the train booking, or if you think you need help - go to the Info desk - which is for sure there for you at most of the main train stations - they should have explained to you that you should switch locations on the carriage, because after all, trains can be split up… as any good German knows.

And also about the cards, just use cash, I mean, come on. Visa some local coins at the airport lounge or wherever…