I purchased three 30-day Xbox Game Pass Ultimate codes from seller gamemania. They were non-stackable codes; I had to wait for each to expire before using the next. I used the first two without a problem. When I attempt to use the third code after the second month expired, I found that the code had already been redeemed. I provided screenshots of my Microsoft account and the chat with Microsoft confirming that it wasn't used in my account. Eneba refused to refund the purchase because the code was used after my purchase. They said that the seller has ways to confirm this directly with the publisher, which they "could not ignore". Considering that I know for certain that I neither used the code nor gave it away, I believe that gamemania resold my code. You can buy legitimate keys through Eneba but customer service will not help you if you get ripped off, even if you provide proof.