I realized that someone methodically downvotes my answers. This guy knows that serial downvotes may be automatically reversed by the system. Usually he downvotes three my answers per day, but not every day (see my reputation changes at 03/06/2014, 04/06/2014, 06/07/2014). I don't think this is a simple coincidence because
downvotes occur almost at one time, with no comments
there is a downvote of my question which got Good Question badge
there are questions that were downvoted several times, though I believe they are absolutely correct. If someone will point me the mistakes I'll fix them or delete that answers.
Given the third fact I suspect that this guy even bothered to create several accounts to downvote my answers.
I've contated MSE moderators but they told me that they don't have evidence (due to limited permissions) to classify this as serial downvoting. I've sent an e-mail to the commmunity team, but they do not respond.
I believe these are intentional downvotes, so tell me how to stop them?
Otherwise prove me wrong, please.