You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I help you?

USER: I want change my reservation as my plan to meet my friend is postponed. Can you help me with that?

ASSISTANT: May I know your name please?

USER: My name is William Thomas.

ASSISTANT: Sorry to say, there is no reservation on your name in our database.

USER: Ok, thank you for the information.

ASSISTANT: Thank you for opting us.