PDR II/Share is no scam. It is a professional fundraising firm, there are a number of similar companies out there.
The way it works is, a charity or other non profit, like a political campaign, gives one of these fundraising companies a list of several thousand supporters and has the fundraising firm call them all to ask for money or other support.
Callers don't leave messages because normally the computer dialer does not even put a real person on the line if the phone isn't answered by a person.
And people get lots of calls/calls don't stop because PDR II doesn't control who it calls. The non-profit tells it who to call, often they have duplicate records for one person or multiple records per house. Sometimes, also, two or more of the non profits who hire PDR II have the same household on their supporters list.
Bottom line: PDR II can end up calling the same house 3 times a day because one charity has a separate record for both a husband and wife and then another political cause has the household listed again.
Why do nn-profits hire PDR II? Well, setting up a call center costs a huge amount of money and a charity that has two or three fundraising drives a year can't afford to have one, so it is most economical for these groups to basically pool resources and hire a firm like PDR II.
Any PDR II caller will take your number off the call list, but its not PDR's call list you are removed from. Your name is removed from that one organization's call list. If someone else wants PDR II to call you next week it will because it has no idea. PDR II doesn't keep records on people, the data belongs to the organizations and is returned to them immediately after the fundraising drive.
Also, the 'Do Not Call List' does not matter, that list applies only to for profit companies. Because PDR II is calling on behalf of charities and other non-profits these calls are exempt.
Finally, not answering will only guarantee more calls. Each campaign lasts anywhere from one to four weeks. The computer keeps dialing a house's number until a caller records a refusal/gift/unavailable/etc. Best option, pick up the phone and say what you want done for that organization's calls.
The only problem with answering and asking to be taken of the list is that the person on the other end will explain that you have to call the charity/political organization and request to be removed from the list. The Share Group is just a contractor who has no control over the actual list. You may also get calls from the same number again but under contract with a different charity.
At least this is what I've been told the few times I have answered their calls. My preferred solution is to add the number to my contacts and make the phone not ring when they call.
You make it sound so logical and businesslike. PDR II harasses people for money. Anyone who thinks it is a civil, reasonable practice to make 20-60 unsolicited calls to a private home over 3 weeks has truly lost their way. I only hope that the Bible is correct and you reap what you sow.