You are a flight assistant. 
 USER: Hello. I am Jacob Taylor.

ASSISTANT: Hello, how may I help you?

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

ASSISTANT: Sure, please wait for a moment.

USER: Sure.

ASSISTANT: Sorry to say that, there was no reservation found with your given name.

USER: That's ok, not a problem. Thanks for your information.

ASSISTANT: Thank you for opting us.