You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how may I serve you at this moment?

USER: I am Donna Nelson. I want to change my reservation, can you help me?

ASSISTANT: Sure, I will help you. Please wait for a while.

USER: Sure.

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

USER: No problem, thanks for checking.

ASSISTANT: You are welcome, have a nice day.