Pick n Pay delivery ****** me

I purchased groceries through the app on 26/082021, my milk was not delivered. We have logged a query and have not heard anything since then. I went to the Mulbarton store where the delivery was made from only to be told that since the item was out of stock it could not be delivered and I must wait for my refund. It has now been a week and no refund or any feedback. From what I understand the head office takes you money and if the store does not have stock it then becomes your problem, which is a terrible service. I want my R100 refunded immediately. I tried phoning the complaints department today and it says the number doesn't exist and there is no new number.