We had a similar experience in Austria. We were going from Switzerland to Germany and would be passing through Austria (for all of five minutes!)

We told the ticket seller in the Swiss station that we would need train tickets for that small portion. Unfortunately we were not clear that we had first class passes and he sold us second class tickets.

We were comfortably ensconced in our compartment when the Austrian ticket collector came by. The other man in our compartment argued with him in German and then paid some money. It was our turn. We found out that we had the wrong class tickets and we had to pay for new tickets or move to the second class. I remembered that Rick Steves had said that the restaurant car was classless so we left our luggage and spent the money on a coffee break instead. The conductor came along and told us gloatingly that our seats were gone. Anyway by the time we had finished, we were in Germany and Richard and I and our two teens found another compartment with equally comfortable seats!

Frances Toronto, Canada