You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I assist you today?

USER: I would like to spent some more days with my grand parents, please help me in changing my existing reservation.

ASSISTANT: Sure, please mention your name for checking your reservation.

USER: My name is Nicholas Roberts.

ASSISTANT: Please give me a moment.

USER: Sure, take your time.

ASSISTANT: Thanks for waiting, there is no reservation found under your name.

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

ASSISTANT: Welcome, have a great day.