You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I serve you?

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

ASSISTANT: Sure, please wait for a minute.

USER: Ok.

ASSISTANT: Unfortunately, there is no reservation found with your name.

USER: No problem, thank you for your service.

ASSISTANT: Thank you for choosing us.