You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how can I help you?

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

ASSISTANT: Please wait a while.

USER: Sure.

ASSISTANT: There is no reservation on your name in our database.

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

ASSISTANT: Thank you for opting us.