Tia Maria Siamese/Balinese review: kitten with congenital defect 1

I wanted a lilac point short hair Balinese so I started calling breeders to see if they had kittens. Maria Ryder of Tia Maria Siamese/Balinese had a litter about to be born, and it turned out there was a lilac lynx point, so we agreed that he would be mine. She sent me videos of him and one had him and another kitten with him. She said in the video that it was his sister, his sister was his best friend, and why didn't I take her home with me too. She said they were twins, born in the same sac, with the same placenta and same umbilical cord, how rare! And that they lived for each other and had never been separated. I was touched by this and agreed, after negotiating a price, to take both kittens. She has a clause in her contract that the kittens have to be seen by a vet within 72 hours and I asked her about that. She called me (we had been texting) and said that was for people who already had animals and that for me, she would waive this requirement and it was fine to take them when their next shots were due, so I did, which was three weeks after I picked them up from her. The vet found a big heart murmur in the female kitten. I alerted Maria and she said she was sure it was nothing because the kitten had been checked by her vet and was fine, that my vet probably just mistook what she heard because probably the kitten was nervous. She looked up my vet and saw that my vet also does alternative healing like Reiki on animals, and questioned my vet's abilities. She asked if I would be willing to have a third opinion and I said I was taking the kitten to a cardiologist and that would settle the matter. I invited her to call my vet and discuss it with her. My vet said she was acerbic and rude and disbelieved her, said the kitten had been fine, her vet had cleared her, and there's no way she developed a murmur in just the time I had had her.
The cardiologist found a murmur grade 5 (it goes from 1 to 6, 6 being the worst) and strongly urged me to return the kitten because "this is not a benign murmur." The cardiologist asked me to return in four months and have another ecocardiogram ($640 a pop) to see how she was progressing and said at that point she would opine about whether or not she could be spayed, but at this point she doubted we would be able to spay the kitten because she would die under anaesthesia. I had the cardiologist's report sent to Maria's vet and I called Maria after her vet had reviewed it. Maria said her vet told her it was a membrane that perhaps had a pinhole in it, and then the pinhole tore and made a big murmur. This is not what happened; it's a congenital defect and it happened during her development in the womb.
Maria refused to refund me the price of the kitten and said if I was going to bring her back, it had better be soon (Why? Was she thinking of re-selling her?). She said I could exchange her for another kitten, but she had no other kittens to exchange her for and no idea when she would be breeding again. So basically I am stuck with a kitten with a severe congenital heart defect who can't be spayed and whose life will be cut short because of the defect. Note how her story changed -- first it was impossible the kitten had a murmur because it couldn't have developed in the three weeks I had had her and the kitten was fine when I picked her up; next it was that the murmur only developed in the three weeks I had had her because the kitten was fine when I picked her up. The vet never listened to this kitten's heart, is what happened. Please don't buy from this breeder. My vet believes she knew the kitten had a defect and that's why the story about them being twins (they look nothing alike) and inseperable, etc., and urging me to take the female as well. I don't know, but it seems likely. At any rate, I ended up with a kitten with an inoperable congenital heart defect.