You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how may I help you today?

USER: Could you please change my existing reservation?

ASSISTANT: Sure, I can change your reservation right now. Before that I need to know your good name please?

USER: I am Jerry Williams.

ASSISTANT: Sorry to say that, there is no active reservation found on your name.

USER: No problem, thank you for checking.

ASSISTANT: Thank you for choosing us.