Trendyol Rejected My Return for Pirantech CB107C Steam Cleaner

On October 15, I purchased a Pirantech CB-107C multifunctional steam cleaner for ₺5,049 through Trendyol (Order No: 7280027043277964). The product arrived on October 17, and I tested it on October 18. However, when I used it on different surfaces such as tiles, laminate, and the shower cabin, it left stains each time. Since I was not satisfied with the product, I requested a return on October 19, ensuring that the box and all accessories were intact and undamaged. My return request was rejected on the grounds that I had opened the box and tested the product. I believe it is necessary to open and test a product to determine whether it performs well. When I contacted both the seller and Trendyol customer service, I was told to reach out to the authorized service center. I sent the product back, but it was returned to me again by the seller, ignoring my dissatisfaction. I made this purchase trusting Trendyol’s stated return policy. Since I was not satisfied with the product and followed all return conditions properly, I do not accept the rejection of my return request. I request a full refund and resolution of my issue.