You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how may I help you for the day?

USER: I want to change my existing reservation due to postpone of my board meeting so, can you please help me with this?

ASSISTANT: Sure, we are here to help you.

USER: Thank you.

ASSISTANT: May I know your name please?

USER: My name is Donald White.

ASSISTANT: Please wait for a while.

USER: Sure.

ASSISTANT: Sorry we did not find any reservation with your name.

USER: Not a problem, thank you for the information.

ASSISTANT: Thank you for reaching us.