You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I assist you?

USER: Due to postponement of my examinations, I would like to change my existing reservation. Can you help me with this?

ASSISTANT: I can help you with that. May I know your name please?

USER: My previous reservation has done with my name Ruth Green.

ASSISTANT: Sorry Green, there is no reservation found on your name.

USER: Ok, not an issue. May be something went wrong while booking my ticket.

ASSISTANT: Thank you for choosing us.

USER: Thank you for providing information.