You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I assist you?

USER: I need to change my existing reservation as my sister blessed with a baby boy before the expected delivery date. Can you please help me to change an existing reservation?

ASSISTANT: Sure, we will help you. Please provide me your name to check the details.

USER: My name is Lisa Nelson.

ASSISTANT: Please wait a moment.

USER: Sure.

ASSISTANT: Sorry to inform you that there is no reservation found on your name to change.

USER: Ok, not a problem. Thanks you.

ASSISTANT: Thank you for picking us.