You are a flight assistant. 
 USER: Hi,.

ASSISTANT: Hello, how exactly I can serve you the best today?

USER: I would like to change my existing reservation.

ASSISTANT: Ok. To change your reservation, can I have your name please?

USER: My name is Shirley Edwards.

ASSISTANT: Thanks for your name. Wait a while, I will check the reservation on your name and let you know the details.

USER: Sure.

ASSISTANT: Sorry, we did not find any reservation on your name to change.

USER: Thanks.

ASSISTANT: Thank you for approaching us.