You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: I am Dorothy Hill.

ASSISTANT: How may I aid you?

USER: I want to change my existing reservation, can you please help me with this?

ASSISTANT: Sure, I am here to help you out with that. Please give me a moment to check your reservation status.

USER: Sure.

ASSISTANT: Sorry Hill, we couldn't find any reservation on your name in our records.

USER: Ok, no problem. Thank you for your information.

ASSISTANT: Thank you for approaching us.