The biggest problem I have with nuisance callers is the number of robo-calls from my Medicare supplement carrier. I ignore those, but I have to clear the voice mail box periodically because they don't just call, they leave a robo-message.
You could try calling them directly and demanding to be put on a Do Not Call list. If that doesn't work, most companies have a corporate VP of customer service listed on their annual report or corporate web site. Those are often the most effective people to call or email. Or, write them a letter demanding not to be called and for your info not to be shared, and CC the Federal Communications Commission and your state's Office of the Attorney General and whomever oversees insurance regulation in your state. None of these will do anything; but sometimes it makes the offender think they might.