They have called me a few times in the past few weeks, no messages were left. When I called back blocking my number I got an automated message 'hello, to be placed on our do not call list, press 1" One and done. Probably a telemarketer in Montgomery county, MD Aspen Hill area
If you blocked your number when you called them back, pressing "1" would have done nothing to take you off their call list. They'd have no idea what your number was. You probably shouldn't worry too much that you missed an opportunity here, though. There's no reason to believe that they'd take you off their list if you asked them to. After all, their unsolicited call to you was against the law in the first place.