You are a flight assistant. 
 USER: Hello. Margaret Miller here.

ASSISTANT: Hello, how may I assist you?

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

ASSISTANT: Sure, I will help you with this.

USER: Thank you.

ASSISTANT: Please wait for a moment.

USER: Sure.

ASSISTANT: Sorry Miller, there is no reservation found as per your name to change your reservation.

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

ASSISTANT: You are welcome.