You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How may I help you?

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

ASSISTANT: Sure, I will help you.

USER: Ok.

ASSISTANT: May I know your good name please?

USER: I am Jack Roberts.

ASSISTANT: Sorry, there are no reservation found on your name.

USER: That's ok, thank you.

ASSISTANT: Thank you for reaching us.