You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How may I assist you?

USER: Patrick White here. I need to change my existing reservation as my sister blessed with a baby before the expected delivery date.

ASSISTANT: Sure, I am here to help you out. Please wait for a while, let me check your previous reservation.

USER: Ok.

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

USER: That's ok, thank you for your help.

ASSISTANT: Welcome, thank you for reaching us.