Am not happy with their service

I have placed and order on the 9th of December I got my items on the 20th, when I received them not everything that I order was there, on the 19th I received an email that some items where out of stock,what puzzles me is that when I order it should let me that the items are out of stock on their portal.

On the 20th I send banking details for refund till today no refund, I have returned an item on the 10th I haven't heard that the item is received and they will process the refund, waiting for the refund of items that was out of stock and refund and for the return item.