One of these assholes incessantly calls up my grandmother (and everybody else in her building) daily, proceeds to scream at her when she denies owning a computer, insisting she does. Then calls her a liar (that she is lying she does not own a computer) until she unwillingly hangs up the phone... upset and confused as to why some young man is calling and yelling at her.

They're all coming from random phone numbers, and there seems to be literally nothing you can do to stop it. Apart from screening every one of her calls for her.

There really are some scummy people out there, unfortunately.