You are a flight assistant. 
 USER: HI.

ASSISTANT: Hello.

USER: I am Christine Young.

ASSISTANT: How may I be of your service?

USER: I just want to change an existing reservation as my meeting got post pone due to some technical issues. Can you help me?

ASSISTANT: Sure, we are here to help you.

USER: Thank you.

ASSISTANT: Please wait a moment I will check the reservation list.

USER: Ok.

ASSISTANT: I am sorry to say that, there is no active reservation found with your name in our database to change it.

USER: No issue. Thank  you.

ASSISTANT: Thank you for approaching us.