The first rule of business, and of life, should be: keep your promise. If you break a promise, you risk losing trust forever. And there’s no more important commodity than trust. I recently enlisted a service that lost a potential customer for life over a $6 promise. And, it was for something I was going to pay for anyway. If you’re in it for the long haul (and if you’re not, you’re going to lose anyway), then you must always, always, always keep your promises (or grovel and take advantage of circumstances out of your control to show the customer how much you value them)