You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I assist you?

USER: As my plans to attend a seminar got postponed due to some issues at San Francisco, can you please help me in changing my existing reservation to San Francisco?

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

USER: I have previously reserved my ticket with the name Larry Miller.

ASSISTANT: Please allow me a minute to check you reservation status in our database.

USER: Sure, take your own time.

ASSISTANT: Larry Miller, there is no active reservation found under your name to do modifications in that.

USER: Oh! That seems something went wrong while booking the ticket previously.

ASSISTANT: Yes, may be that's the reason.

USER: Thank you for your service.

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