You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I assist you?

USER: As my plan to visit my grand mother's home got postponed. So, can you please help me out in changing my existing reservation?

ASSISTANT: Sure, I can help you with that. May I know your good name please?

USER: Sure, my name is Nicholas Collins.

ASSISTANT: Nicholas Collins, there is no active reservation found under your name to do changes in that.

USER: That's ok, thank you for checking.

ASSISTANT: Thank you for choosing us, have a great day.