You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello.

USER: I am Sarah Parker.

ASSISTANT: How can I assist you today?

USER: Would it be possible to change my reservation?

ASSISTANT: Sure, I will help you.

USER: Thanks.

ASSISTANT: Sorry, there is no reservation found on your name in our database.

USER: It's ok, thanks for your information.

ASSISTANT: Thank you for reaching us.