You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I help you?

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

ASSISTANT: Sure, may I know your name to check the reservation?

USER: My name is Jeffrey Hernandez.

ASSISTANT: Sorry, there is no reservation with your name.

USER: Ok, that's not a problem. Thanks for your information.

ASSISTANT: Thank you for reaching us.