Surely you can see that a post dripping with sarcasm, like this one, is not the ideal way to represent your company online. It’s not a matter of finding words that will "please everyone"—you’re right, you can’t. It's about showing the minimum level of courtesy and professionalism. Just because you can't please everyone doesn't mean it's not worth trying to please as many people as you can--or at least trying not to offend as many as you do.
Obviously there are some people that will be obstinately dissatisfied--but you won't know someone is like that unless you make an honest effort first. Even once you have decided that a person is beyond any effort to please, then for the sake of the on-lookers, surely a courteous reply will serve you better than venomous sarcasm. In any case, why have your first response be one that insults the person, or dismisses the validity of their concern?
This makes you look bad. Until you realize this, you're going to continue to alienate potential customers. That may not concern you--you seem pleased with the 20,000 that you brag about--but the way you've comported yourself in these forums has guaranteed that I won’t become #20,001.