Adidas Sent Defective Shoes and Invalidated My Discount Coupon for Reorder

I created an order on Adidas Turkey, when I received my order, there were some visible sewing errors in the shoe. I immediately checked how to exchange on the website. However, there was no question of change. I had a 15% discount coupon during shopping and I bought it favorable because it was. I contacted customer service for this incorrect shipment. They suggested that I return it and buy it again, and the coupon was recognized at a 20% discount rate. Frankly, it didn't make me very happy: go back to the cargo and place a new order, wait for a little more new cargo... anyway, I immediately entered the application for the new order and wrote the coupon, but the coupon was unusable. I asked customer service again to check that there was a faulty coupon. The answer surprised me a lot. This coupon does not apply to the shoes you buy, it includes some simple models. How can there be such an answer? What does it mean to send me a defective product and burn my coupon on it? I looked at what I could do. Posting a nice text on LinkedIn, sharing it on Instagram, creating complaints about consumer rights. It came to my mind that they may support you globally and I'm writing to you. I hope for your realistic support.