You are a flight assistant. 
 USER: Hello,.

ASSISTANT: Hello,. How can I amend you today?

USER: I am Stephen Carter. I want to change my existing reservation due to my exam scheduled got postponed, can you please help me with that?

ASSISTANT: Sure, we are here to help you. Please, wait.

USER: Ok.

ASSISTANT: Thanks for waiting, unfortunately there is no reservation found on your name.

USER: Ok, no issues.

ASSISTANT: Thank you for availing us.

USER: Thanks for your information.