You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How can I assist you at this moment?

USER: Please change my existing reservation owing to an emergency.

ASSISTANT: Sure, I am ready to help you with that. Can I have your good name please to check your reservation status?

USER: My name is Donna Martinez.

ASSISTANT: Ok Donna, please wait a moment to check existence of your reservation.

USER: Sure.

ASSISTANT: Sorry Donna Martinez, no reservation has found under your name to change.

USER: Thanks.

ASSISTANT: Thank you for choosing us, have a good day.