Tired of being sent substitutes I did not order

I really like Takealot and order regularly, but I'm fed up with being sent a similar item instead of the one I ordered. Each time that I've returned such an item and request the one I ordered, I've been informed that the one I ordered is out of stock. Takealot seem to deliberately substitute products instead of admitting to incorrect stock records. According to chatbots that I've asked, there's nowhere to set one's profile to communicate to Takealot that you're not interested in substitutes. Also, Amazon is said to be far less likely to send substitute products. Why would Takealot give the international giant such a huge advantage to take over their South African market? If it's out of stock, why not be honest, admit it to the customer, and keep more accurate stock records in future?