You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I serve you today?

USER: My name is Jonathan Lewis, I want to change my existing reservation due to health issues.

ASSISTANT: Ok. I will help you for sure. Please wait, I will check the reservation list and let you know.

USER: Sure.

ASSISTANT: Thanks for your time. We are sorry to inform you that no reservation was found on your name.

USER: No problem, thank you.

ASSISTANT: Thank you, Have a nice day.