You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I help you?

USER: Due to sudden change in my planned date of journey, I would like to change my reservation. Can you please help me out with that?

ASSISTANT: Sure, may I know your name for the existing reservation process?

USER: Thank you for accepting my request, I have reserved it on the name of Nicholas Lopez.

ASSISTANT: Wait a while, kindly.

USER: Sure, take your time.

ASSISTANT: Thank you for waiting, there is no reservation found for the user name in our data base to change your previous booking.

USER: Oh! I think the ticket was not booked properly while I am booking. Anyway, thank you for the information.

ASSISTANT: Thank you for choosing us. Have a nice day.