You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I assist you now?

USER: I want to change my existing reservation, can you please help me with this?

ASSISTANT: Sure, I will help you with that. Can I have your good name please to check your reservation status?

USER: I am Amy Johnson.

ASSISTANT: Ok, please wait a moment.

USER: Sure.

ASSISTANT: Sorry Amy Johnson, no reservation has found under your name to change.

USER: Ok, no problem. Thank you for your information.

ASSISTANT: Thank you for choosing us, have a good day.