Product Return and Refund Issues on the Mango App

I used the Mango app to buy something on November 19, 2023. The order number is DT3M46. Mango had to cancel one product because there weren't enough items available. I had to wait for my delivery, but they didn't refund the canceled item until December 1, 2023. I finally got my refund for the item that got canceled after making multiple calls to customer support. It happened on December 1, 2023. I canceled the item through customer support because I hadn't received it on the same day. I was told I would get my money back and I gave them my IBAN, but it's now December 18, 2023 and I still haven't gotten a refund. The refund deadline mentioned in the Mango app has already passed, and from December 1, 2023, to December 19, 2023, no refund has been given. I'm writing to say that I'm really unhappy with this situation.