You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I support you?

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

ASSISTANT: Sure, may I know your name please?

USER: Benjamin Miller.

ASSISTANT: Please wait for a while.

USER: Ok.

ASSISTANT: Thanks for your time, there is no active reservation found in your name.

USER: That's ok, thank you.

ASSISTANT: Thank you for choosing us.