Trendyol Refused Return of Unopened Toner

I bought a toner from Print Bilgisayar via Trendyol but realized I ordered the wrong one. I returned it without even opening the package, and before bringing it into my home. However, they refused to accept the return, claiming it wasn’t suitable for resale. Despite my efforts to return the unopened product immediately, they did not take it back. This has been a frustrating experience, as I followed all steps to ensure the product was in perfect condition for return, yet I’m still stuck with an item I can't use.