Like Deborah said, since so much time passed, there is probably little recourse at this point.
However...
This is obviously not a problem caused by you, nor is it a problem that could have popped up recently. The snake was born that way. The breeder had to have known about it.
If you breed and sell Ball Pythons you can see a obvious birth defect such as this. Esp. if you handle and sex the snake.
This is highly un-ethical and while I'm glad you are keeping the little one and giving it its best shot, it doesn't change the fact that the breeder did you wrong.
They should refund your money. That is in my humble opinion. IF I had a hatchling such as this I would consider myself lucky just to find someone willing to take it for free and give it a chance.
I could never sell it, esp. hiding the fact that it has a birth defect.
Since the breeder is ignoring you at this point just shows she knows she did wrong, and has no intention to do right.
What I would do is keep the snake, continue to do my best to see it thrive. I probably would expose the seller, though. Not because I like to stir up drama, but simply to warn others.
But this is just in my humble opinion![]()