You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how can I assist you?

USER: Owing to an emergency, my planned trip to Washington got postponed. So I want to change my existing reservation.

ASSISTANT: Ok, may I know your name please?

USER: Sure, I have a recent reservation with name Benjamin Nelson.

ASSISTANT: Ok, please wait for a moment.

USER:   Sure.

ASSISTANT: Sorry, there was no reservation found with your name.

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

ASSISTANT: Thank you for opting us.