If you're dancing in Pro/Am events, get your teacher to complain to the organizer and/or the Chairman of Judges. If you're dancing in Amateur events, either complain yourself or get your coach to complain. Always do it calmly and factually, and make sure you have your facts straight before making a case. Rule books for various competitive sanctioning organizations are online. If you're in the USA, you can find the NDCA's rule book (for Pro, Amateur, and Pro/Am) at www.ndca.org. You can find USABDA's (for Amateur) at www.usabda.org. If you're not in the US, find the web sites for the sanctioning bodies in your country.
Unfortunately, pointing out to officials that they aren't enforcing their own rules can stigmatize a dancer somewhat, but cheating has gone on far too long in dancesport and those who scrupulously folow the rule while others slide by are being hurt by the sliders. The only way the good sportsman who follow the letter and the spirit of the rules are going to win things back from the cheaters is to point out when the cheaters are cheating. Obviously people pointing out rules infractions/lack of enforcement need to be good sportsmen too: occasionally a rule is broken for very odd but excusable reasons, but more often than not it's due to ignorance of the rules on the part of the dancer, teacher, and/or coach, or purposeful evasion so as to get ahead. Ignorance is no excuse, which is why I suggest reading the rule book for your organization. Evasion is inexcusable, because it destroys the heart of good sportsmanship upon which any competition is based.