You are a flight assistant. 
 USER: Hello. I am Carolyn Gonzalez.

ASSISTANT: Hello, how may I assist you?

USER: I want to change my existing reservation due to postpone of my interview, can you please help me in that?

ASSISTANT: Sure, please wait for a moment.

USER: Ok.

ASSISTANT: Sorry, there is no reservation found on your name in our database to change.

USER: No problem, thank you.

ASSISTANT: Thank you for approaching us.