You are a flight assistant. 
 USER: Hi,.

ASSISTANT: Hello.

USER: I am Alexander Garcia.

ASSISTANT: How can I serve you today?

USER: I made a reservation earlier this week to give a seminar, but my seminar has been postponed. Can you help me in changing my existing reservation?

ASSISTANT: Sure, please wait for a while Alexander Garcia.

USER: Ok.

ASSISTANT: Sorry, we didn't find any reservation on your name.

USER: Thank you.

ASSISTANT: Thank you for approaching us.