We have just bought tickets from Basel to Cologne and are very certain that the train offers reservation seats as the train is ICE. However, during check out, the app removed our selection for seats and now we are left without any seat reservations. May I know how do we add seat reservations without having to purchase another set of tickets? We have tried to unselect the ticket and only select the seat reservation on both the SBB website and mobile app to no avail. The seats are likely out for selection as well since we are able to get another ticket to Amsterdam on a later date with seats reservation. Anyone has any idea on how to just purchase the seats? Thank you!