You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello.

USER: I am Benjamin Jackson, need to book a flight ticket. Could you help me?

ASSISTANT: Sure, can I know the source and destination?

USER: I want to change my existing reservation.

ASSISTANT: OK. Give me a moment.

USER: Sure, please check.

ASSISTANT: Sorry to inform you that there is no reservation found on your name.

USER: OK.

ASSISTANT: Thank you for reaching us Benjamin.

USER: Thank you for your support.