You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I assist you?

USER: I want to change my existing reservation due to change of my schedule. Could you please help me?

ASSISTANT: Sure, may I know your name?

USER: I am Mark Evans.

ASSISTANT: Ok, please wait a minute.

USER: Sure.

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

USER: No worries, thank you for the information.

ASSISTANT: Thank you.