You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I help you?

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

ASSISTANT: Sure, can you share your name?

USER: Justin Collins here.

ASSISTANT: Sorry, there is no reservation found under your name.

USER: No problem, thanks for your information.

ASSISTANT: Thank you for reaching us.