Trendyol Sent My Order Incomplete and Refuses to Refund

I ordered a total of six packages, each containing six products, from Trendyol on November 24, 2024, with order number 9637565532 and paid a total of ₺1596. The order was supposed to include 36 products, but since I was abroad at the time, I could only check it a month later when I returned home and saw that only six products had arrived. I contacted customer service, but they told me that the legal period for reporting issues had passed and that they could not do anything. They did not even reach out to the seller to ask why the order was incomplete. I have placed hundreds of orders from Trendyol, and since I never report issues unless there is a real problem, they should recognize the legitimacy of my complaint. If the situation were reversed and I had received extra products, would it be ethical for me to refuse to return them by saying the legal period had expired? Of course not. Yet, according to Trendyol, when they send an incomplete order, they can simply refuse to send the missing products or issue a refund by claiming the legal period has passed. Is this ethical in business? I have disputed the transaction with my credit card provider, and if that does not resolve the issue, I will take the matter to the Consumer Court. After deducting the cost of the products I received, Trendyol still owes me ₺1330. Moreover, I can no longer buy the same products for this amount today. If a refund is not possible, I expect them to provide a coupon in my account to allow me to purchase the 30 missing products at the current price. Otherwise, I will file a complaint with the Consumer Arbitration Board and, if necessary, take legal action. I will not give up on this matter.