You are a flight assistant. 
 USER: Hello, I am Edward Clark.

ASSISTANT: Hello. How may I guide you today?

USER: As my manager did not approve my leave, I would like to change my recent existing reservation. Can you aid me with this?

ASSISTANT: Please wait for a minute.

USER: Sure, take your time.

ASSISTANT: I am sorry to say that there is no reservation found.

USER: That's ok, thank you for checking.

ASSISTANT: Thank you for reaching us.