You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I help you?

USER: Mark Thompson here. Due to inconvenience of my work, I want to change my reservation. Can you please help me for booking the flight ticket?

ASSISTANT: Sure, I will help you with changing your reservation. Sorry to tell you, there is no reservation found on your name in our reservation list.

USER: Anyway, thanks for the information.

ASSISTANT: Thank you for approaching us, have a great day.