You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I help you today?

USER: I want to change my existing reservation, due to some health issue. Can you help me?

ASSISTANT: Sure, I am here to help you with that. Can you please share your name?

USER: Ok, I am Mary Lopez.

ASSISTANT: Please allow me a moment.

USER: Sure.

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

USER: Ok, not a problem. Thank you for your help.

ASSISTANT: Thank you for reaching us, have a nice day.