Miss Manners: I’m a helpline worker. How can I politely end the call?

My concern is how to end the conversation politely when the business is over, but the caller doesn’t need to prolong the conversation. After the two parties have said certain phrases (for example, “Call me back if you need me” or “Thank you and have a nice day”), instead of hanging up, the caller starts repeating their thanks, continue to wish me well, or even start an unrelated conversation (“Did I tell you you remind me of my cousin?”).