You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I help you?

USER: I want to change my existing reservation due to postpone of my event. Can you please help me?

ASSISTANT: Sure, please share your good name?

USER: I am Lisa Anderson.

ASSISTANT: Sorry, no reservation found on your given name.

USER: No worries, thank you for the information.

ASSISTANT: Thank you for choosing us.