Amazon Delivered Canceled Order and Now Refund Is Missing

I ordered a Casekoo phone case for my S26 Ultra through the Amazon app around March 11. The delivery took so long that I decided to pursue other options, and I cancelled the order in the app because I no longer needed the product. Despite this, the Casekoo case has just been delivered to me now, even though I had already cancelled it. When I check my Amazon app, the order is not visible in my order history, so I cannot easily manage a return or see the current status of the transaction. Since I cancelled the order due to the delay and no longer need this item, I request a full refund for this purchase. I would like this to be resolved as quickly and simply as possible, and if a return is required, I expect clear instructions and a hassle-free process.