thanks. I finally got hold of an immigration office by phone as well (the first time that’s ever happened and I’ve tried them all over Thailand lol).
Yeah, it seems overstay gets recorded either way but going to the immigration office just will cost you more because you’re paying for that visit as well and you’ll pay per overstayed days too. I guess all it does is to give you a bit of piece of mind that you won’t get detained at random.
So, the best way seems to be to just leave and hope for a re-entry.