You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. Can you pleas tell me how can I guide you?

USER: Unfortunately, I want to change my existing reservation, can you please help me in this condition?

ASSISTANT: May I know your name?

USER: Sure, my name is Anthony Allen.

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

USER: That's fine.

ASSISTANT: Thank you reaching us.