Establishing the return on investment of customer support is not an exact science. Because it relies on the expected actions of the client in future interactions with a company, it lends itself to a certain amount of speculation. It is possible to grasp the effect however, and to see how significant customer support will be when it comes to allocation of capital.
Losing Future Revenue
Obviously, this is something that every company would strive to avoid. In a competitive marketplace, it often only takes one bad customer service experience for a company to lose a customer to a competitor in the industry. It should be pointed out what that is likely to cost a company; not only are the immediate sales numbers going to be affected, but if you were to extrapolate what the average client would spend on future purchases and the loss of profit from every one of those, it is easy to see how expensive it is to lose a customer.