Personal opinion here, but I would suggest you ask for your money back and go through a breeder vs. a pet store, or at least go to a pet store that specializes in reptiles. I've had luck buying from both breeders online, and local reptile specific pet stores, but I wouldn't send anyone to a big box store (which sounds like what you did) to get any pets. I don't even purchase fish from places like Petsmart because of poor care and them buying their animals from the cheapest source, which is typically mill-type breeders.
I'm really sorry that this is your first BP experience. This store you went to doesn't sound like they have their stuff together, and for a new keeper, really any keeper, you want to know that your snake is healthy and eating well from the start, and it doesn't seem like the store can tell you either of those things.