You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how may I help you now?

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

ASSISTANT: Sure, I can help you. Please wait a moment.

USER: Sure.

ASSISTANT: Sorry, we couldn't find any reservation on your name.

USER: Ok, no problem. Thanks for your information.

ASSISTANT: Thanks for consulting us, have a nice day.