You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello.

USER: James Smith here.

ASSISTANT: How may I guide you today?

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

ASSISTANT: Sure, I will help you with that. Please wait for a minute.

USER: Ok.

ASSISTANT: I am sorry to say that there is no reservation found.

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

ASSISTANT: Thank you for contacting us.