I think you are right to be upset, most good breeders only want to sell to "pet only" homes, except for a few exceptional dogs that could possibly used for breeding, and then they would have to go to the right breeders home, not just anyone's home. Were the dogs AKC registered, and did you sell breeding rights? Did you use a contract? Unfortunately. you can't trust some people, whether outright liars, or just careless, so many people will just go ahead and breed a pet only dog. Joey's breeder had it in the contract that I was not to breed Joey, and she could obtain possession of the dog, if I tried to sell him, or I wasn't treating him right, so I really didn't buy Joey, I adopted him, and she is the real owner, so I better be a good mama.
Some breeders are even neutering their dogs before they leave home, just to be safe. What's really sad about the whole thing is that the better dogs, generally, are less likely to be bred, and it really makes me wonder about the future for yorkies.