You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How may I be of your service?

USER: I am Barbara Carter. I just want to change an existing reservation as my meeting got post pone due to some technical issues. Can you help me?

ASSISTANT: I understand your request, I'll help you in changing an existing reservation.

USER: Thank you.

ASSISTANT: Please wait a moment I will check the reservation status.

USER: Ok.

ASSISTANT: Thank you for waiting, sorry to inform you that there is no reservation found by this name.

USER: No issue. Thank you.

ASSISTANT: Thank you for opting us.