Eneba Ignored My Support Ticket After Selling a Previously Used Steam Key

I purchased a Steam game key for Arc Raiders from Eneba approximately one month ago under the order number o-ya3zata. When I tried to activate the key on Steam, I received a message stating that the key had already been used, and I was therefore unable to add the game to my account. After noticing that the key was already used, I contacted Eneba support. They informed me that they had escalated the issue to the seller and that it would be resolved within 1–5 business days. However, it has now been about two weeks since that message, and I still have not received any response or solution from either Eneba or the seller. I request a full refund for this purchase, as the product provided was not usable and I was unable to activate the game on Steam due to the key having already been used, and the promised resolution within 1–5 business days was not fulfilled.