A customer is NOT always right BUT as a customer he or she always deserves to be treated right. Even if a customer is wrong and ill-mannered, management should handle this with proper decorum and respect as always expected from any business entity at all times. Be assertive yet polite in explaining to the customer when they are at fault. And as a costumer, you should also learn to act politely and with decency. You can communicate to the management your dissatisfaction or complaint in a dignified manner and not abusively or rudely and creating a scene as you do so. It only shows so much about you as a person on how you act on such situations. I would never demean myself in front of people even if my point is right by acting rudely. I can do it with propriety.