Can't be authentic Prada

This is such VERY poor quality, it can't possibly be authentic Prada. Within the first month of use, the elastic closure stretched out and eventually broke. By the end of the school year many of the seams started ripping and one of the straps ripped out of the seam. How can I get a refund for this obvious fake? Prada wouldn't stand for this poor quality. The backpack I bought at Walmart lasted longer than this.