Cancelled order but item still advertised to avoid applying a discount or promotion

I usually have good purchases on TakeAlot and use them all the time. My Son signed up on takealot and they were running a promotion for first sign ups that you get a R300 off for a purchase made over R500.00. So he purchased the items and did an instant EFT as payment. The order for the one item was cancelled. so obviously the purchase amount was less than R500 and this disqualifies the discount code but yet the same item that was cancelled is still being advertised. A refund of R65.00 reflects in his takealot account but the entire sale was R463.00. I see the same type of reviews for promotional items so this is obviously a loop hole they are using to avoid giving people the discounted items