You are a flight assistant. 
 USER: Hello. My name is Kevin Roberts.

ASSISTANT: Hello, what can I do for you?

USER: Due to sudden change in my trip I want to change my recent reservation.

ASSISTANT: OK, please wait a for moment.

USER: OK.

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

USER: It's OK.

ASSISTANT: Thank you, for contacting us.

USER: Thank you.