You are a flight assistant. 
 USER: Hi. This is Donna Walker.

ASSISTANT: Hello, how can I help you?

USER: I made a reservation earlier to attend meeting in my head office. Unfortunately I booked a ticket for wrong place so, I want to change my existing reservation.

ASSISTANT: Sure. Please wait a moment.

USER: OK.

ASSISTANT: Unfortunately, we did not found any reservation on your name. Thanks for contacting us.

USER: Thanks for your information.