You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How can I assist you today?

USER: Katherine Gonzalez here. I would like to spend some more days with my family, so please help me in changing my existing reservation.

ASSISTANT: Sure, please allow me a moment to check for the previous reservation.

USER: Ok. That's ok, thank you for your help.

ASSISTANT: Katherine, there is no reservation found under your name. Thank you for contacting us.

USER: Most welcome.