Defective product not fixed, replaced or refunded

Takealot refused to take back a defective item because I don't have the manual and the usb cable that came with the item. Here's an extract of their terms that they refuse to adhere to:

7: Charges and refunds If you return a defective product to us, but you fail to return all of the accessories and parts that were sold with that product, we are entitled to (subject to applicable law) refuse the return, or only to replace the item that you did return; or to estimate the value of the missing accessories and parts and to credit or refund you in respect of the returned item only.