Refunds

Refunding voluntarily is the mark of an ethical business. In practice this is not always possible. An extremely annoying or misbehaving client will not receive considerations other clients receive. Misbehaving diminishes the spirit of even an ethical business person to fully cooperate. In mathematical game theory this is called tit-for-tat. It is a strategy of  ethical behavior that has some merit. Tit-for-tat works both ways. When one person cooperates it inspires the other to cooperate. As the cooperative relationship grows both the client and the businessperson enjoy the rewards of greater consideration. It is a pleasant and rewarding interchange and one of the great rewards of having a business. Refunding monies owed is a good policy and it disciplines the business person in a way that their first response to this situation is to refund the money avoiding future conflicts and the gradual erosion of their ethical standards. see ethical split

Note: Tit for tat is not always the best approach to dealing with conflict in a business.  A small business has finite energy. Getting involved in a game can drain resources and energies that could be better used with really important problems. There is a learning curve to business. Pay your dues, refund the money even if an annoying person upsets you and be wiser in choosing your customers and the defining the terms under witch you will deal with them in the future.