Dissatisfied Takealot Client

I ordered and paid for a pack of 20 AA Duracell batteries from Takealot. I only received a pack of 12 AA batteries. This morning they were willing to collect the pack of 12 batteries but refuses to replace the wrong delivery with the correct one. This was their reply: "Unfortunately, we no longer have stock of this item in order for us to investigate the matter. Once the return has been received at the warehouse, will we credit you the amount paid. Should you prefer a refund instead, please inform us so that we can have the refund processed." To me this makes absolutely no sense and I am a dissatisfied client of Takealot. Today the product is on special again?????? I use to be a loyal client for many years.