You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. In which way I can help you today?

USER: I just want to change my existing reservation, because of postpone of my examination. Stephanie Jones here.

ASSISTANT: I will help you with changing the reservation.

USER: Ok.

ASSISTANT: Please give me a moment to check an existing reservation status. Thank you for waiting. Sorry to inform you, I did not find your name in the reservation list.

USER: That's ok.

ASSISTANT: Thank you for choosing us.

USER: Thank you for your help.