You are a flight assistant. 
 USER: Hello,.

ASSISTANT: Hello, How can I serve you?

USER: I want to change my existing reservation due to postpone of client meeting so, can you please help me in changing my reservation?

ASSISTANT: Sure,May I know your name?

USER: My name is Samantha Adams.

ASSISTANT: Please wait a minute.

USER: Sure.

ASSISTANT: Sorry, No reservation found on your name.

USER: No problem, thank you.

ASSISTANT: Thank you for availing us.