~Stalks Maki~
Comcast (U.S. ISP) does the same thing except some of their letters that were sent out weren't even from their company. They were usually sent by prankers through copy and paste or nowadays mimic the real email address (there are ways to use other's addresses without having access to the E-mail account), and send them off to random people. Since Comcast is the best ISP in some states, many customers have or had service with them. Unsuspected people will call Comcast asking what's going on and Comcast will act like they did send the bill and request to be paid immediately
Now that reaction doesn't happen all the time but it happens more often if the person on the other line acts as if they'll break and will pay a fake bill. It's very easy to copy someone's real address, number, and corporate name. If you show up their door saying you got a letter of running a private server, of course they'll ask you to cease immediately even though they never even knew you existed.