Quality work does not guarantee quality service. Just because your work may be superior to that of other concrete contractors in your area doesn't mean you provide the same level of quality on the service side.
Though the ability to achieve superior results is crucial to any job, the ability to work with people and treat customers with respect, appreciation, and congeniality is equally important. An old saying in the medical profession is that the three most important components to patient retention are availability, affability, and ability--in that order. This is as true for concrete contractors as it is for physicians.