You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How could I serve you today?

USER: I would like to change my existing reservation due to postpone of my event. Could you please help me?

ASSISTANT: May I know your name please?

USER: I am Kenneth Hall.

ASSISTANT: There is no reservation found with your given name.

USER: No worries, thank you for the information.

ASSISTANT: Thank you for choosing us.