Pick n Pay - Refund

I made a purchase via pick n pay online app and paid for the goods and after an hour of deducting from my account I was told that the items were out of stock and that they will refund and when they delivered the items that were on stock I found out that they delivered an item that I did not order and I took it back to the store at Cornubia Mall and was told that I will get my refund the following day. I have sent numerous emails and them responding saying they will get back to me and it has been 3 days without any solution from their side