Online store takes 3x longer delivery & incomplete package arrives

Ordered five books from CNA's online store as they promise delivery in SA within 2-5 business days. Placed my order on the 29th of October and by the time the package arrived on the 21st of November, it was 16 working days.

The package only had 3 of the 5 books I ordered inside. I contacted CNA on the 15th of February and until now, I have no contact from them. Their emails claim, "we will respond within 48 hours" but it takes 8 days for me to email AGAIN so they can promise another response in 48 hours. Such a lame excuse for an "online store" and at this point, they have ****** money (my statement reflects the amount for all 5 books was deducted) for products they haven't delivered.