Bad shopping experience at Clicks store

Good day, today I was dissatisfied and disappointment at Clicks store in Tsakane mall, after they refused to sell me baby food that is on special/promotion, them telling me that certain doesn't want to scan it their signage doesn't say excluding certain items. I had to substitute for something that I don't want knowing very well that I bought the same products a week ago because I know they on promo, now just because it doest scan whose fault its that....