You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how can I guide you for today?

USER: I want to change my flight reservation as my trip got postponed. Can you please do that for me?

ASSISTANT: Can you please provide your name?

USER: Sure, my name is Sarah Nelson.

ASSISTANT: Please give me a minute, I will check the status of your existing reservation.

USER: Sure.

ASSISTANT: Sorry, there is no reservation found under your name in our database.

USER: No problem, thank you for checking.

ASSISTANT: Thank you for contacting us, have a nice day.