Bershka Won't Cancel Order That's Not Shipped, Just Because It's Being Prepared

I bought the Bershka brand from Trendyol on November 25 for 1790 TL per month. The next day I realized that I had chosen a small piece, I immediately bought my size again and wanted to cancel it, but I cannot cancel it because it is in the preparation phase. I can't understand this, the product that hasn't even been shipped is allowed to be canceled after a day and my money is officially used. The billing date for my card, which will be 12 December, has arrived and the money I will send back to the desired location will be deducted from me. Trendyol app never helps. I can not tell my problem. This is not a situation that suits such a brand. I will send the products back depending on the person and I will never shop there.