You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how may I assist you?

USER: I need to change my existing reservation owing to an emergency.

ASSISTANT: Sure, I will help you in change of flight ticket reservation. May I know your name please?

USER: I am Sarah Hernandez.

ASSISTANT: Please wait. Thanks for your time. Sorry there is no flight reservation on your name to change it.

USER: Thank you.

ASSISTANT: Thanks for contacting us.