You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, welcome to flight booking agency. How can I guide you for today?

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

ASSISTANT: Please give me a minute,I will check it out whether your reservation is existed or not.

USER: Ok fine.

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

USER: No problem. Thank you for your help.

ASSISTANT: You are welcome. Have a great day.