You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how may I assist you?

USER: Please change my existing reservation which I have done previously. with my name Janet Hernandez.

ASSISTANT: Ok, please wait for a mean while.

USER: Sure, get back with the status of my reservation.

ASSISTANT: Sure, I will get back to you.

USER: Thank you.

ASSISTANT: Sorry Janet, there is no reservation found as per your name to change your reservation.

USER: It's ok, thanks for checking.