Maybe it will help to think of these calls like junk mail? Without junk mail, the price of a stamp would be considerably higher... but yeah, that sucks.
Here's a review of iOS10 call-blocking apps which recommends the free app, Hiya
Hiya does require that users provide access to their contacts, which may deter some people from using the app over concerns about where their information might wind up. The company’s privacy policy is incomplete and a bit unclear about what it does with specific data, including contacts, but a company spokesperson provided extensive and official clarification on request.
Hiya says it uploads a user’s phone number and contact phone numbers to add to its global whitelist, because contacts tend, as it notes, not to be spammers. The app also uses your contact information to help with calls placed within the app, one of its features. The company says it keeps contact data otherwise private, and doesn't sell it to third parties, nor does it use the information to market to your contacts. Hiya also says it doesn’t give your phone number to third parties.
Here's another article with call blocking options. You might be interested in "Call Bliss" (not free) to only let known callers through.
If you're still receiving unwanted solicitations after registering your number with the do not call registry, then you should report the numbers to the FTC.
If you received an unwanted call after your number was on the National Registry for 31 days, report it to the FTC.
If you are being called by an actual person, instead of a "robo-call" recording, just immediately talk over them and tell them to cease and desist, that the call time and number are being reported to the FTC, and that you will personally sue them and their company if the continue to harass you. They usually hang up before I can get all that out and it seems to do a good job of preventing them from calling back.
Good luck!
From the Do Not Call Registry FAQ:
What are the penalties for breaking the law?
Those who violate the National Do Not Call Registry or place an illegal robocall can be fined up to $40,654 per call.
Also:
If you get unwanted calls from many different numbers, look into a call blocking solution. There are online call blocking services, call blocking boxes, and smartphone apps that block unwanted calls. Research whether the service costs money and whether it’s effective. Do an online search to look for reviews from experts and other users.
