My New Jack Wolfskin Jacket Deformed Quickly

In November, I purchased what I believed to be a long-lasting winter jacket from Boyner, based on the sales associate's recommendation. Confident it would keep me warm in my cold workplace, I splurged, paying nearly ₺7,000. However, shortly after, the jacket began to shed feathers, sticking to the inner lining as pictured. When I consulted the store, they assured me it was normal. After wearing it for just a month and a half, I followed the washing instructions precisely. To my dismay, after washing, the jacket was reduced to a mere lining, devoid of any feathers. Despite sending it for inspection, Boyner provided no help regarding refund or exchange. Paying ₺7,000 for a jacket that barely lasted a month and a half is unacceptable. Given my current financial situation, buying a new one is out of the question. I'm seeking a resolution and urging for assistance.