Players making their own ruling.

Five years of hardly playing, and not directing at all, ended recently when I found myself directing a two section session with Nine High and Open sections. I was impressed by the resoucefulness of players in finding different ways of trying to upset my control of the event. In the Nine High I spotted players putting their cards back in the wrong pockets. The board had been turned 90 degrees to give declarer more room. Then the same thing happened at the same table on the first board of the next round. After I had corrected them slight confusion ensued, and they started to bid the same board again, not realising till dummy went down. Their slightly guilty demeanour caused me to dive in just as they were again returning their cards with the board 90 degrees out. Later, in the Open section my attention was drawn to a score of a small slam making an overtrick on the lead of an ace, which was not ruffed. Inquiry at the relevant table brought the explanation that a defender had revoked, not winning the revoke trick nor any subsequent trick "so we transfered an extra trick to ourselves". When I asked why they had not called me, the answer was "We didn't want to bother you. We know the rules." "You don't know them well enough" said I, and corrected the score. In the Nine High I had contented myself with gentle chiding, followed by less gentle chiding. However the players who had awarded themselves an overtrick were experienced enough to know perfectly well that they should have called me.So my question is what penalty would have been appropriate, and should there have been two penalties, one for not calling the director, and one for entering an incorrect score in their own favour?