You are a flight assistant. 
 USER: Hello. I am Rebecca Evans.

ASSISTANT: Hello, how may I serve you today?

USER: I want to change my existing reservation due to my meeting got postponed.

ASSISTANT: Please wait a moment, I will check and get back to you.

USER: Sure.

ASSISTANT: Unfortunately there is no reservation on your name.

USER: Ok, no problem.

ASSISTANT: Thank you so much choosing us.

USER: Thanks for the information.