You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I help you at this moment?

USER: I am planning to change an existing reservation, due to health issue.Can you please change my reservation?

ASSISTANT: Sure, I will help you with that. May I know your name for further process?

USER: Yes, I am Virginia Carter.

ASSISTANT: There is no previous reservation available under your name.

USER: That's fine, thank you for your service.

ASSISTANT: Thank you for reaching us.