You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I assist you today?

USER: My name is Nancy Evans. I want to change my existing reservation due to postpone of my conference.

ASSISTANT: Ok. Please wait I will check the reservation on your name and get back to you.

USER: Sure.

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

USER: No problem, thank you for your quick response.

ASSISTANT: Thank you for contacting us.