Obviously sir you do not know the adage of a bad customer experience and what that customer will do. A customer who experiences bad service that tells 10 others of their experiences, causing those 10 person to have that thought in their mind, and if anyone else mentions something about that specific vendor, it jars that from memory and they tell the experience of their friend. You can see how this can soon mushroom and could easily become known by hundreds of persons. Soon you notice your phone rings less, and less and less are walking into your store.
Perhaps this is already happening to you and that is causing your anger as demonstrated by your "radio nazi" comment. Less people speak of a positive customer service experience, but more people will speak of a negative customer service experience. The customers aren't at fault it, it is YOU the vendor that is tarnishing your reputation throw smart aleck comments, promises of shipping orders and then sitting on them. Granted, sometimes parts aren't always in stock, but that is something you the VENDOR should be up front about it.
You may think you are a great businessman, but take a moment to read the comments from the consumers, they don't sound happy. It would be at this point that I'd take a step back, and ask the question "what are we (vendors) doing wrong that our customers are so unhappy?"
True, you may have thousands of satisfied customers, but one upset customer can really rock the boat, and in this case, it looks like there are several boat rockers. Personally, I don't see this coupon thing as that big of an issue, and was going to not comment on this thread until I saw your comments. I, as well as many others after reading them, likely uttered the words "FU, I sure won't be doing business with a company that treats customers like that."
A good place to illustrate good customer service is a grocery store. They are large, and often it is difficult to find a certain item and we end up asking an employee for assistance. Most employees will respond with "aisle 7 for that" but the best employees will say "here, follow me, I will show you where it is located," and take you right to it, asking if they can help with anything else before returning to what they were doing. That is an example of excellent customer service, leading to loyal and returning customers.
Far too many people work in customer service for just a paycheck and could care less about the customer really. Having a chip on your shoulder serves no purpose but alienating your customers, driving them away to competing vendors and surely this is not what you want happening, but making sniping comments does nothing but make that wound fester more.
It's your business, run it as you see fit, but remember, customers... consumers make the final decision of whom they will do business with, so when sales start dropping and the phone rings less and less you have only yourself to blame, not the customers.