You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: I am Kenneth Lee.

ASSISTANT: How can I help you?

USER: I want to do some modifications in my previous reservation, can you please help me?

ASSISTANT: Sure, I will help you to do modification. Please give me a moment.

USER: Ok, take your time.

ASSISTANT: Sorry, no reservation found on your name to change.

USER: That's ok, thank you for checking.