Did you ever provide your phone number at voter registration? I made this mistake once and got added to dozens of text lists, Democratic and Republican. Never had a problem from the usual leaks.
I am not a Louella or a Brenda, more of a "Joe" or "Frank".
I am quite sure that ActBlue just creates a list of names, then create a wardial list and assign those names to a number.
Asking them to stop just confirms your number to work. And yes, it's ActBlue because they have specifically identified themselves as such more than once.
They probably did a fuzzy merge and your number (or a number typo'd to yours) got associated with some random old lady.
That's how I got on the lists of all the scummy PACs targeting elderly voters that Adam Bonica called out recently. I only figured it out because the cash for homes cold contacts trying to lowball his house will actually respond.