We had booked the service departing Cologne at 18:55 on 1 December, arriving into Karlsruhe at 20.58. We had paid for a seat reservation. I've just been notified that that service is no longer running due to an alteration to the timetable, that my ticket can now be used on any train ("Zugbindung aufgehoben") and that I can transfer my seat reservation. All direct services on that day now take at least 3 hours instead of 2. In the "DB-Navigator" it tells me to select an alternative service, yet when I click on it I just get a message that no alternative services have been found. Anyone any idea what's going on? I have no idea how I am now meant to select an alternative service and transfer my seat reservation. Maybe I'll have to contact customer services but thought I would ask here.