Well it sounds to me like you did everything right, i find it rather unreasonable that the breeder refuses to replace your snake. Since you have other bps that are healthy and doing fine i highly doubt it was a husbandry error on your part. If i were the breeder i would have offered to replace your snake or give you a credit towards another one of the amount you paid for the PYB. When i start to breed and sell my snakes im gunna make it a point to try and offer the best customer service to buyers that i can.