You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I aid you?

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

ASSISTANT: May I know your name to check your reservation?

USER: Cynthia Carter.

ASSISTANT: Ok, please wait for a while.

USER: Ok.

ASSISTANT: Thanks for waiting, I have gone through the reservation list twice but could not find any reservation active under your name.

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