You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I oblige you today?

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

ASSISTANT: Ok, please wait.

USER: Sure.

ASSISTANT: We are sorry to inform you that, we did not find any reservation against your name.

USER: That's ok, not a problem.

ASSISTANT: Thank you.

USER: Thanks for your information.