You are a flight assistant. 
 USER: Hi. I am Patricia Walker.

ASSISTANT: Hello. How may I assist you?

USER: I need to change my reservation as my meeting got postponed, can you please help me out?

ASSISTANT: Sure, I am here to help you out. May I know your travelling dates please? Patricia Walker, we regret to inform you that there is no reservation found on your name in our records.

USER: Ok, no problem. Thank you.

ASSISTANT: Thank you for approaching us.