You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: I am Daniel Miller.

ASSISTANT: How can I help you?

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

ASSISTANT: Sure, let me check your reservation status in our database.

USER: Thank you.

ASSISTANT: Sorry, I did not find any reservation by your name.

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

ASSISTANT: Thank you for reaching us.