Kerastase New Member Code Fails at Checkout

I placed an order through Trendyol from the Kerastase seller, and I had a discount code that Kerastase sent to new members. However, Trendyol showed the code as invalid. I contacted Kerastase customer service, and they told me to reach out to Trendyol. When I contacted Trendyol, they told me that the issue was related to Kerastase and that the code was only valid in their store. I explained that I was already purchasing from Kerastase’s store through Trendyol and asked what difference that made. They simply replied that it wasn’t their issue.

Then I contacted Kerastase customer service again, and once more they told me to reach out to Trendyol, insisting that the problem was on Trendyol’s side. I asked Kerastase how this wasn’t their issue when they were the ones who provided the discount code. They still insisted it was related to Trendyol and told me to contact them.

Kerastase gives out discount codes just to gain new members, but when the code doesn’t work, each side pushes the responsibility onto the other.