You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I help you today?

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

ASSISTANT: Sure, please wait.

USER: Sure.

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

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

ASSISTANT: Thank you for reaching us.