Ah the perils of being a grammar / spelling nazi - I've been there many times, sometimes I just can't contain myself and the person you're "trying to help" is never pleased unless they've specifically asked for help with their grammar and spelling. And then there is the extremely high probability of making a mistake with the written word in pointing one out. Yikes. Planks, eyes, splinters and all that biblical stuff. It's an old problem.
So back to the topic - how to "educate" a designer breeder who clearly has had many similar previous attempts by disgruntled shelter workers, vet staff, and registered breeders.
So the reply - there's plenty of good material for use available in the knowledge base for puppy mills on the RSPCA website.
This breeder's comment about breeding for temperment is open to dispute.
As is the "rarely found in shelters" - a reputable breeder who cares about their dogs - would take the unwanted dog back (as one Amstaff breeder here has done).
I'm willing to bet they cannot guarrantee temperment, health or shedding qualities of their dogs and they don't take their puppies back when they don't meet the owners expectations.
People who buy puppies from pet shops are often uninformed as to the breeding conditions at the source of the puppies or they are deliberately made to feel sorry for the last puppy of the litter to be homed (ie the litters are deliberately split up to encourage this), and that new owner is ill prepared for puppy ownership. They haven't got adequete fencing, they don't know what vet bills they're going to be up for (annual vaccinations, if nothing else}, or what kind of food to feed or how to train a dog to be a well behaved companion.
I heard my neighbours kids going "Sit Gemma, Sit Gemma" hmm repeating command, saying dog's name after command - duh. Need to say name first or leave it out, and deliver "sit" - with a treat to lure position, so puppy always gets it right - for at least the first 100 times. And then you can start to get intermittant with the treats.
But there's not a lot I can do at this time.