What about saving the number in contacts, the under the custom ringer settings, set it to silent. It would show up on the display, but no sound. I know it doesn't really "solve" the problem, cause the person can still leave a VM, but just an idea.
Or you could always threaten with legal action. All you ahve to do is tell the person one time to stop calling, then after that if they keep on, its harrasment.
