You are a flight assistant. 
 USER: Hi, I am Amanda Roberts.

ASSISTANT: Hello, how can I be of your helping hand?

USER: Owing to an emergency, my brother engagement got postponed. So I want you to change my existing reservation.

ASSISTANT: Sure, we are here to help you. please wait a moment, I will check your details and revert you with the status.

USER: Sure.

ASSISTANT: Sorry to inform you that there is no reservation exist on the name Amanda Roberts.

USER: Ok, no worries at all. Thank you for your kind service.

ASSISTANT: Thank you for contacting us.