You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I assist you?

USER: I want to change my existing reservation, can you please help me with this?

ASSISTANT: Sure, I will help you get this resolved. May I know your name please?

USER: My name is Michelle Martinez.

ASSISTANT: Please wait.

USER: Sure.

ASSISTANT: Thanks for waiting. But I am sorry to say that there is no flight reservation on your name to change it.

USER: No problem, thank you.

ASSISTANT: Thank you.