No stock again and discount lost

If I could, I would rate 0 stars. This is now how many times where goods are ordered and only 75% of the order can be fulfilled. Always out of stock and the biggest issue is, that with items on special. So for instance, you order 3 items where you are suppose to get 25% discount, then they only have 2 of the items resulting in loosing the 25% discount. This is not my problem so why should I pay normal price if they cannot supply? I expect a refund and feedback.