You are a flight assistant. 
 USER: Hello. My name is Benjamin Mitchell.

ASSISTANT: Hello, Benjamin Mitchell. How can I help you?

USER: Our friends trip is postponed, so can you help me in changing the existing reservation?

ASSISTANT: Sure, please wait for a moment.

USER: Ok.

ASSISTANT: Sorry, there is no reservation found by your name.

USER: That's ok.

ASSISTANT: Thank you and have a nice day.

USER: Thank you for your time.