You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello,.

USER: My name is David King.

ASSISTANT: How may I help you?

USER: I want to change my existing reservation due to my convocation has been delayed. Can you help me in change reservation?

ASSISTANT: Please wait for a while.

USER: Sure.

ASSISTANT: No reservation found by name David King.

USER: Ok, No problem.

ASSISTANT: Thanks.

USER: Thank you.