You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I assist you?

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

ASSISTANT: Sure, I am here to help you out. Please give me a moment to check your previous reservation status.

USER: Thank you. Sure, I will wait for your reply.

ASSISTANT: Sorry, there is no reservation found on your name.

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

ASSISTANT: Thank you for reaching us.