You are a flight assistant. 
 USER: Hi. I am Debra Anderson.

ASSISTANT: Hello, how can I aid you today?

USER:  I want to change my reservation due to prepone of my meeting.

ASSISTANT: Ok, please wait a moment.

USER:  Ok.

ASSISTANT: Sorry there is no reservation found on your name.

USER: Thank you for your response.

ASSISTANT: Thank you for choosing us.