You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I assist you?

USER: Can you help me in changing my existing reservation?

ASSISTANT: Sure, I am glad to help you and may I know your name please?

USER: I am Karen Wilson.

ASSISTANT: Please give me a moment.

USER: Sure.

ASSISTANT:  Thank you for waiting, I have checked in reservation list to change your ticket but could not find any reservation with your name.

USER: Ok, no problem. Thanks for the information.

ASSISTANT: Thank you for reaching us, have a nice day.