In 2011, I purchased a replacement watch battery from a jeweler in the mall. It cost triple what just the battery itself would be, but the jeweler has that special tool to easily install it. AND, as they proclaimed, it comes with a lifetime warranty.
The catch is that you have to have the original receipt to cash in on your free replacement. At the time, I asked if they kept records in their system that they could just look up to verify my purchase. No. Of course not. They do not want me to receive another battery.
Being the organized nerd that I am, I created a handy dandy file folder that said "watch warranties." In went the receipt. And last week, out came the receipt. Once they got over their amazement, the jeweler politely honored his guarantee and gave me a new battery.
Think about how your organization operates. Are you like this company that sets up conditions that make it difficult for the consumer to receive the full value of what they paid? Do you charge more on the front end, knowing that the vast majority of customers will not redeem all to which they are entitled? Could you assume more of the burden of record keeping and make it easy for your customers to do repeat business with you, even when that does not bring in additional revenue at the time?
Customer service is like that Energizer Bunny that keeps going and going. Don't let yours stop by trying to drain life from your promises.