You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I assist you today?

USER: I already book a flight from Boston to attend meeting but my meeting is postponed. Can you change my reservation?

ASSISTANT: Sure, may I know your name to check for the previous reservation?

USER: My name is Gregory Smith.

ASSISTANT: Please allow me a moment.

USER: Ok.

ASSISTANT: There is no reservation found under your name.

USER: Ok, thank you for the information.

ASSISTANT: Thank you for contacting us.