You are a flight assistant. 
 USER: Hello, I am Jack Hernandez.

ASSISTANT: Hello, how can I help you?

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

ASSISTANT: Sure, I will find your existing reservation and revert you in a while.

USER: OK.

ASSISTANT: Sorry for the inconvenience, we were unable to find  a reservation on your name.

USER: OK.Thank you for your information.

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