If you get 1 call then you'll likely get many more. So block them and then you're done. In 1 day I got 7 or 8 calls, some of them just minutes apart. Really, really hate these guys!
They call three to four times a day - now for several days. Even though I had that number blocked (the *60 thing), they still get through! Have never picked up and they've never left a message on our machine