You are a flight assistant. 
 USER: Hello.

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

USER: I am Donald Roberts, want to alter my reservation due to an emergency. please help me.

ASSISTANT: Sure, I can help you with that. Please hold on a moment, I will check your previous reservation status.

USER: Sure, take your time.

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

USER: It's ok, thank you for your help.