You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how can I assist you?

USER: I need your help in changing my existing reservation, can you please help me with that?

ASSISTANT: Sure, may I know your good name please?

USER: Sure, my name is Elizabeth Hill.

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

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

ASSISTANT: Thank you for approaching us.