German phrase
Ich wünsche eine Umbuchung in ~.
Meaning
I would like to change my booking to ___
When to use it
It requests a rebooking. This polite wording suits airline or travel agency staff.
Example dialogue
Ich wünsche eine Umbuchung in die Businessklasse.
I would like to change my booking to business class.
Das geht, kostet aber einen Aufpreis.
That is possible, but it costs extra.