You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I aid you at this moment?

USER: Could you please help me to change my existing reservation due to postpone of my client meeting?

ASSISTANT: Sure, we are here to help you.

USER: Thank you.

ASSISTANT: May I know your name to check your reservation status?

USER: My name is Sharon Harris.

ASSISTANT: Ok, please wait for a while.

USER: Sure.

ASSISTANT: Sorry, we couldn't find any reservation with your name.

USER: Not a problem, thank you for checking.

ASSISTANT: Thank you for choosing us.