You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I aid you?

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

ASSISTANT: Sure, I will help you. Could you please provide your name to check your previous reservation status?

USER: I am Margaret Johnson.

ASSISTANT: Ok Johnson, please be on hold.

USER: Sure.

ASSISTANT: Sorry to inform you that, there is no reservation found with your name in our records.

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

ASSISTANT: Thank you for approaching us, have a great day.