You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I aid you?

USER: I want to change my existing reservation. Could you help me with that?

ASSISTANT: Sure, I can help  you out. May I know your name?

USER: Benjamin Hall here.

ASSISTANT: Give me a minute.

USER: Ok.

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

USER: That's ok, no problem. Thank you.

ASSISTANT: Thank you for picking  us.