You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I help you?

USER: I have booked a ticket earlier to attend project exhibition, but recently the venue got changed to Houston. So I want to change my existing reservation.

ASSISTANT: May I know your good name?

USER: I am Timothy Martinez.

ASSISTANT: No reservation found with your name.

USER: Ok, not a problem.

ASSISTANT: Thank you, have a great day.

USER: Thanks for your valuable time.