You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I help you today?

USER: Due to some personal issues, I would like to change my existing reservation. Please help me out.

ASSISTANT: Sure, I am here to help you with that.

USER: Thank you.

ASSISTANT: Ok, may I know your name?

USER: My name is Jeffrey Hernandez.

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

USER: Ok, no problem. Thank you for your information.

ASSISTANT: Thank you for reaching us, have a nice day.