Hello.
user
Hello, how may I serve you at this moment?
assistant
Is this Central travel agency? Yesterday I booked a ticket to New York through your agency, your agent  by mistakenly booked a ticket  on wrong dates, so I want to change my reservation.
user
Ok, sure I can search with your ticket reservation.Can I know your name?
assistant
I booked a ticket on the name of Margaret Lee.
user
Sorry for the inconvenience, no reservation found on your name in my database.
assistant
That's fine, I will try for other agency.
user
Thank you for reaching us.
assistant
You are welcome.
user