Good for you! Fight them for a refund to pay her Vet bills.
Please do not give her back, these breeders sound beyond awful, and I can only imagine her living conditions there, these types of breeders are just in it for the $ and I seriously doubt they would take care of her if you gave her back, they would probably put her to sleep
The 3 things she has is totally treatable, I know you are doing your best and are tired, but soon everything could be great!
About your neighbor, maybe until things clear up, you can find someone to help her with her Yorkie
