i am planning a journey from Geneva airport to Lenk. Preferably I would travel via Montreux on the train departing at xx19
However, if my flight is slightly delayed and I miss this train, could I then travel via Bern on the train departing at xx32.
i can see that they are priced differently, so if I had already purchased a ticket for the xx19, could I just pay the difference on board the train to the ticket conductor, or would it still be valid without paying more, or would I have to buy a brand new ticket?
Bearing in mind that I might be in a rush if I have missed my intended train.