You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How may I assist you today?

USER: I need to change my existing reservation, Can you please help me with that?

ASSISTANT: Sure, may I know your name.

USER: Alexander Harris here.

ASSISTANT: Sorry, there is no active reservation on your name.

USER: Ok, no problem.

ASSISTANT: Thank you.

USER: Thanks for your information.