At the end of the day, companies are going to make mistakes and get black-eyes over products or projects gone wrong. Some say that successful companies have a batting average that is just above average.
The good companies own up to their mistakes/problems, and proactively go about solving or correcting the issues. The good companies don't try to profit along the way of correcting their mistakes or argue with their clientele about correcting the mistakes.
Every experienced or enlightened business person knows this, and long term business relationships have to be able to endure some bad experiences with all the good experiences.
If you lost some customers due to this problem, you now have a real, honest story to go back with and present. Make that effort and then leave any decisions to do further business with those customers with no pressure.
After that, you've done all that you can do, and you should sleep with a clear conscience.
