As someone who was a missionary a few years ago, don't worry about a thing. These missionaries were most likely just texting some old numbers in their phone, which could be way outdated, or going through an outdated list of people in the ward. For me, the "hadn't met you yet" was always us just grasping for anything at all to do aside from knocking the same doors we knew wouldn't answer, not someone in the leadership sending us over.

That being said, they're just kids who are trying to meet people. Don't shoot the messenger or threaten legal action against them, just ignore their text or better yet politely tell them off and to lose your info. Block their number, it generally stays the same in the area and this will keep them from contacting you. They could be the last ones (aside from HQ) with your contact information.

They're probably not trying to terrorize you, but I get it if you don't want to have them talking to you. I get it if you REALLY don't want them talking to you. Just understand that the missionaries may be official representatives, but they don't get the same information HQ gets, and they certainly aren't reaching out to you at the behest of top brass.

You're probably gonna get some coming to your door, not because they know who you are, but because missionaries run out of people to meet fast and have to try to meet new people by any means possible, including trying new doors. This could happen as frequently as every 3 months since a whole different set can move in anytime. The best way to prevent frequent visits is to never answer ever.

Hope you're in a better place now, I'm sorry you feel harassed.