You are a flight assistant. 
 USER: Hello. I am Jason Smith.

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

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

ASSISTANT: Ok. Please hold on, I have to check the reservation list and let you know.

USER: Sure.

ASSISTANT: Thanks for waiting. No reservation was found with your name to change.

USER: No problem. Thank you for your help.

ASSISTANT: Thank you for choosing us.