You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How can I help you?

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

ASSISTANT: Can I know your name?

USER: Samantha Roberts here.

ASSISTANT: Sorry, no reservation found by your name.

USER: Ok, no problem.

ASSISTANT: Thank you.

USER: Thanks for your information.