Trendyol Schafer Cookware Set Issue

I bought a Schafer brand cookware set (order number 9120071132) from a Trendyol merchant using the Trendyol app. One of the pots that I received has white stains on it. When I discussed this with the seller, they told me that they could arrange an exchange, so I returned the merchandise. However, when I checked today, I discovered that the swap had not happened and that a refund would be sent instead. When I contacted customer support again, I was informed that the product was out of stock. However, I check every day and the same product is always available for purchase from the Trendyol seller. There has never been a day when it was not available. However, I'm being told that it's out of stock. Why is the same product continually being sold if you do not have it in stock? After I mailed the merchandise to you, Schafer brand contacted me and offered to exchange the damaged product. If you weren't going to assist the swap, I'd have submitted it straight to Schafer for replacement. I'm absolutely disappointed. All relevant images related to the issue are included. I request that my grievance be addressed by enabling the exchange and returning the product to me.