What do you do when you buy a puppy from a breeder, and find out 2 days later they have hook, and tapeworms?

I am so upset!! I took my new little baby chihuahua to the vet today because i could see that she probably had tapeworms. I bought this puppy on friday. Anyway, the vet did the whole worm check thing, and she also has hookworms. The vet said she probably got them from her mother. Well my question is shouldn't this have been prevented?? This lady that I bought her from is a breeder, who sells lots of puppies. Now, because of this I have a hefty vet bill for the treatment. I feel that it was her responibility to make sure my puppy was worm free. She said when I bought her that she had been wormed, but I wonder now if she was lying. Anyway........I just want someone's opinion about this. Thanks so much to those who answer.