You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

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

ASSISTANT: Ok. Please wait, I will let you know.

USER: Sure.

ASSISTANT: Ok. Thanks for waiting. No reservation is existed previously.

USER: No issue, thank you for your service.

ASSISTANT: Thanks for availing us, Have a nice day.