You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I serve you for the day?

USER: I am Nancy Wilson. Can you change my existing reservation?

ASSISTANT: Sure, can you please wait for a moment, I will check with your reservation and revert to you.

USER: Sure.

ASSISTANT: Thank you for waiting. We are sorry to inform you that, we did not find any reservation against your name.

USER: Ok. No problem. Thanks for the information.

ASSISTANT: Thank you for reaching us. Have a good day.