
I found the RSPCA useless, but reporting animal neglect to the police as it is cruelty they are supposed to do something as you have reported a crime. (That info I got from the Kennel Club, when I had a similar problem with my daughters dog she had rescued from a puppy farmer).
Also if four or more litters are being bred per year then she must be licensed and all dogs must be seen. If she is not licensed then she is technically breaking the law, but sometimes you have to really push the local council to do anything about this. Also if puppies are being sold then it is something the tax man would be very interested in I am sure.