You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I assist you today?

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

ASSISTANT: Sure, may I know your name please?

USER: Amy Adams here.

ASSISTANT: Ok, please wait a moment I'll check the reservation list.

USER: Ok.

ASSISTANT: Thank you for waiting, sorry to inform you that there is no reservation found by this name.

USER: That's ok, no problem.

ASSISTANT: Thank you for approaching us.

USER: Thank you.