You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I help you?

USER: Can you please help me to change my existing reservation, due to my trip with my friends has been postponed?

ASSISTANT: Let me know your name.

USER: Please check my reservation the name of Steven Evans.

ASSISTANT: Sorry, no reservation found by your name.

USER: Ok, thanks for your help.

ASSISTANT: Thank you.