Never buying from them again

How can a business of this size offer such a poor service? I placed an order online for a R9500 inverter of which they had 1 in stock. 2 Days later while eagerly waiting for my delivery to arrive, I got an email saying that the item I ordered is out of stock??? Then after spending an hour trying to get through to their customer support, I asked to change to another product which the website states they have stock of and again I'm told that the website is wrong, they have no stock. Now I have to wait days to get my money back so that I can order somewhere else.