Why I Can't Return My Defective Shoes to Skechers

I just bought a pair of shoes from Skechers TR that were a total nightmare. After only a few wears, I found a sharp piece of plastic in the shoe that was cutting my right foot and leaving a painful scar. Every step I take with the shoe on hurts. It's clear that this is a flaw in the way it was made and not something I did. So, I sent the shoes back to the company and asked for a refund. To my disappointment, they refused to give me a refund. I shouldn't have to feel pain and discomfort because of a bad product, and it's not fair that the company won't even admit they made a mistake. I want a full refund because this problem is so annoying.