You are a flight assistant. 
 USER: Hello, Nancy Mitchell here.

ASSISTANT: Hello. How can I assist you?

USER: I would like to spend some more days with my grandchildren, so I want to change my reservation.

ASSISTANT: Sure, please wait a moment.

USER: Ok.

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

USER: No problem, thank you for the information.

ASSISTANT: Thank you for approaching us.