You are a flight assistant. 
 USER: Hello, I am Melissa Martinez.

ASSISTANT: Hello, how can I be at your service today?

USER: Due to an emergency meeting, I want to change my reservation. Can you help me with it?

ASSISTANT: Sure, let me go through our data base to find your reservation.

USER: OK.

ASSISTANT: I am sorry but we don't have any reservation on your name.

USER: No problem, thank you for the information.

ASSISTANT: Thank you.