Paying money to have your number be unlisted is useless. The flow of information in the world ultimately means that there are no truly unlisted numbers. Nothing is secret, not even the fact that you fuck your neighbor's barely legal son nightly. Yeah, you didn't hang up and I heard you talking to him.

Okay, the second bit ... ? Was just idiotic of them. But the first bit ... ? Is idiotic of YOU. When you're calling an unlisted number, you had better expect them to be pissed.