Non delivery by Builders Wharehouse

I have recently bought three items online from Builders warehouse, 1 to pickup in Centurion and two for delivery. The one article was delivered three weeks after purchase. The pickup article disappeared and they refunded me. The third article they phoned to say that although they show stock it was not available but they haven’t refunded me. If you phone them you get a runaround and if you chat with them they promise to get back to you but nothing happens. They are useless