You are a flight assistant. 
 USER: Hello, I am Barbara Robinson.

ASSISTANT: Hello, how may I assist you?

USER: As part of my schedule I make a reservation earlier to attend client meeting. Unfortunately meeting got delayed on week. So I want to change my existing reservation. Can you be my helping hand?

ASSISTANT: Sure, please wait a moment meanwhile I'll check the details of your reservation.

USER: OK.

ASSISTANT: Sorry Barbara, in my database I didn't found any details regarding your reservation.

USER: It's ok, not a problem. Thank you for your service.

ASSISTANT: Thanks for reaching us. Have a nice day.