Hello @crypto.piotr, thanks for sharing this information.
It is something very serious what you describe and an abusive attitude of someone to whom you give your trust and take advantage of it to make profits without your consent.
Particularly I have no knowledge that something like this has happened to me but I'm going to take a look to see what there is, although I think that they are not interested in an account with a low voting power.
Thanks friend.
Pr EV
He signed up for Steemvoter. In the Steemvoter ToS, they clearly state that you authorize them to use one of your votes a day on a post from one of the BuildTeam services. If you don't want that, you can pay a small fee for a premium account.
Technically, consent had been given here, he probably just didn't read the terms of service.