Oh goodness, It sounds like you were taken advantaged of with these two. As much as you love them I would probably give them up to a yorkie rescue and take the loss of 1,000$ what you paid. I would see what the vet says but it sounds like this situation isn't good.
May I ask how come you would agree to let them pick your dogs out for you?
I would be shaking my head and walking away before someone would tell me THEY got to pick the dog I was going to have for the rest of their life? that sounds to me like they picked the ones with the problems to drop off on you.
As mentioned there isn't such a thing as a micro or mini or teacup. These people are pathetic.