Takealot's appalling order/delivery system

I ordered an item and inadvertently used my holiday home address for delivery. I immediately tried to change this to the correct address but was told that I could not do and should cancel the order. When I tried to cancel the order I was told that I could not do this until the item was with the courier for delivery. I have now received a message that delivery will be made tomorrow. I have tried again to cancel but as of yet have not had a response. The absurdity of this is obvious. Takealot's order system is appallingly inadequate. Be very careful of using this online seller.