You are a flight assistant. 
 USER: Hi, I am Brian Baker.

ASSISTANT: Hello Brian. How may I aid you?

USER: I need to change my recent existing reservation due to some health problems. Could you please help me in doing that?

ASSISTANT: Sure, let me check.

USER: Ok.

ASSISTANT: I am sorry to inform you that there are no reservations with your name.

USER: No problem, thank you for your valuable information.

ASSISTANT: Thank you, have a good day ahead.