Oysho Leggings Poor Fit and Bad Customer Service Issue

I bought a pair of leggings from the Oysho store in Ankara/Gordion. I wore them for the first time three days after my purchase. Within the first hour, I was uncomfortable with the waistband slipping down and bunching up. I’ve used many different models of Oysho leggings without any issues, including the same product in a different color and size.

I went back to the store with the leggings on to show the issue, and despite the correct size, I was told it might have stretched from a previous customer trying it on. I was advised to leave them for inspection. The next day, I returned them for review. I was never contacted, and when I called, I was told the leggings had no defect. The inspection was apparently done by the store manager and the team.

I requested a reevaluation and received no callback. After my second request, I was told again that there was no issue with the leggings. If there's no problem, why am I experiencing this? I paid twice the standard price for these leggings, only to face discomfort and poor customer service. Their inspection form even states there’s no size issue (as shown in the attached image), yet they insist there's nothing wrong and asked me to take the problematic leggings back. I do not accept this resolution and will pursue my legal rights.