You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can  I assist you?

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

ASSISTANT: Sure. May I know your name?

USER: Christine Brown here.

ASSISTANT: Please wait a while.

USER: Ok.

ASSISTANT: Thanks for being waiting. We didn't found any reservation by this name.

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

ASSISTANT: Thank you for opting us.