Utopian Store Refuses to Accept Defective Dress by Free Shipping

I purchased a dress from the Utopian store, and I'm extremely frustrated by their unacceptable response to their own manufacturing mistake. The dress has obvious stitching defects, clearly a production error, yet they refuse to let me return it via free (prepaid) shipping. They actually had the nerve to ask, "Didn't you notice?"—as if it's my fault for trusting their brand quality. I tried to wash out a stain myself at home so they wouldn’t incur additional shipping costs, but it remained. Now, after paying bus fares and tailoring fees, I refuse to spend another cent due to their production error! They’ve been completely unresponsive or slow in their replies, offering no genuine solutions. Utopian, you must immediately resolve this issue: arrange a pickup with free return shipping to correct your defective product and end my frustration now!