You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I provide assistance to you?

USER: My name is Catherine Smith. I want to change my existing reservation due to health issues.

ASSISTANT: Sure, please wait for a while, I will check and revert you.

USER: Ok.

ASSISTANT: We are sorry to inform you, we did not find any reservation against your name.

USER: No problem, thanks for your information.

ASSISTANT: Thank you for approaching us. Have a good day.