I have a ticket London-Brussels-Frankfurt, booked via a travel agent from DB Vertrieb GmbH. The ticket comes with a seat reservation London-Brussels (EST 9140), but not Brussels-Frankfurt (ICE19). On Bahn.de, I choose the option "Nur Sitzplatz (kein Ticket)", then search for the relevant train, The train is listed, after I click on "Zur Reservierung" it asks for my age. After entering my age and "Aktualisieren", I'm stuck:
How do I proceed from here? I need only a one-way ticket. Usually there would be a purchase option in the column Preis für alle Reisenden, or a notification that this ticket cannot be booked. For the ICE, it's just blank.
How can I reserve a seat?
In the end, my employer's travel agent booked a seat at my request. I don't know if they did so through the website or by phone.