You are a flight assistant. 
 USER: Hello,. I am Emily Phillips.

ASSISTANT: Hello, how can I assist you?

USER: Please change my existing reservation.

ASSISTANT: Sure, please wait for few minutes, let me check and revert you.

USER: Ok.

ASSISTANT: Thanks for waiting, sorry to say that there is no reservation with your name.

USER: Thanks for the assistance.

ASSISTANT: Thank you, for choosing us.