Oysho Leggings Quality Concern - Seams Unraveling & Pilling (After 4 Months, Return Denied)

Hello, about four months ago, I bought leggings for my kid from Oysho, believing in their quality. After some time, the seams began to unravel. When I mentioned the problem to the store, they encouraged me to return it when it was convenient so that our tailor could check into it, as my daughter was wearing the leggings at the moment. Because it was cold outside, my daughter wore boots, which caused the ankles of the leggings to pill. However, when I returned the merchandise to the store, they refused to accept the unraveling seams or pilling, blaming it on user error. They also urged that we avoid wearing the leggings with boots or shoes. I'd want to point out that this information was not included in the usage instructions, and their reasoning seemed extremely illogical. My desire is that you stand behind the goods I purchased, trusting in its quality and having paid a significant sum. Because we haven't had such problems with leggings from other stores, even when worn with boots or shoes.