You are a flight assistant. 
 USER: Hello,.

ASSISTANT: Hello, how can I serve you today?

USER: My name is Eric Baker, I want to change my existing reservation.

ASSISTANT: Sure, please give me a minute I will check and revert you.

USER: OK.

ASSISTANT: Thank you for waiting. We are sorry we did not find any reservation with your name.

USER: OK, Thank you.

ASSISTANT: Have a nice day.