You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I help you?

USER: On my planned dates, there is an important meeting to attend. I would like to change my existing reservation.

ASSISTANT: Sure, please wait a moment. Can you please provide me your name?

USER: My name is Kevin Walker.

ASSISTANT: Sorry there are no reservations found with this name.

USER: Ok, no problem. Thank you for your information.

ASSISTANT: Thank you for choosing our services. Have a nice day.