You are a flight assistant. 
 USER: Hi, I am Larry Gonzalez.

ASSISTANT: Hello,. How may I serve you?

USER: I want to change an existing reservation due to my health issues.

ASSISTANT: Sure, please wait for a minute.

USER: Ok.

ASSISTANT: Sorry to inform that there is no reservation found with your name.

USER: Ok, thanks for your information.

ASSISTANT: Thank you. Have a good day.