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

ASSISTANT: Hello Kevin, how may I be of your service today?

USER: I want to change my existing reservation.

ASSISTANT: Sure, just let me check that for you.

USER: OK.

ASSISTANT: I am sorry to say that there is no existing reservation found against your name.

USER: Thank you for your information.

ASSISTANT: Thanks for choosing us. Have a great day ahead.