Help With Fake Follower Traffic

What do you do if you think someone is sending you spam accounts other than going private or blocking them all manually? Are there any other options? Changed password to see if account was hacked. Didn't stop it. I don't believe changing the username works either.

No clue what's going on. Not using any marketing services. And worried that this will change our demographics to something undesirable for brands.

Willing to hire an expert if anyone recommends someone who can fix this.

Unless you want to approve followers manually then there's really no way around it. Bot accounts still target accounts (to follow) if you use certain hashtags as one example.

Most social networks, at some point in time, scrub bot accounts through internal processes or systems that identify those accounts.