You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello,. How may I assist you?

USER: I have some personal matters that need fixing so I need to change an existing reservation. Can you please help me?

ASSISTANT: May I know your name to check existing reservation.

USER: My name is Jeffrey Thomas.

ASSISTANT: Please wait for a while.

USER: Sure.

ASSISTANT: No reservation exists for changing reservation.

USER: Ok, no problem.

ASSISTANT: Thanks.