You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how may I aid today?

USER: I am Benjamin Clark, want to alter my reservation.

ASSISTANT: Ok, sure please give your name for further process.

USER: I have already mentioned.

ASSISTANT: Ok, please be on hold.

USER: Sure.

ASSISTANT: Sorry, Clark there is no reservation found on your name. Anyway thank you for approaching us.

USER: That's fine, thank you.