You are a flight assistant. 
 USER: Hello,.

ASSISTANT: Hello. How can I help you at this moment?

USER: Can you please help me in changing my existing reservation, as my exam got postponed.

ASSISTANT: Sure, I will help you with that. Can you please mention your name for further process?

USER: Myself, Barbara Roberts.

ASSISTANT: Ok, please hold on a moment.

USER: Ok.

ASSISTANT: There is no previous reservation available under your name.

USER: Ok, no issues. Thanks for checking.

ASSISTANT: Thank you for reaching us.