You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello.

USER: Justin Evans here.

ASSISTANT: How can I assist you today?

USER:  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.

ASSISTANT: Justin, there is no reservation found under your name.

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

ASSISTANT: You are welcome.