Another source of expense in any payment system is the cost of handling complaints and questions from the consumers. A customer service operation requires many people, telephones, and computers. Customers are usually confused or irritated, so the interactions are far from efficient. Each customer service call costs a few dollars, sometimes more. If there is no way to resolve a dispute amicably and quickly, there might be several calls associated with the same transaction.
Customer service becomes a serious burden in the micropayment world.
Even if the nominal profit margin is high on individual micropayment, the absolute margins are rather thin. A single customer service call can easily wipe out an entire year's profit on that customer account. And an unhappy customer can put a dent in company's profitability. Therefore, one of the design goals in each of the micropayment systems was a reduction in the number of customer service calls. One potential source of dispute in online transactions is that the customer may claim he did not receive the digital goods he paid for.