Misleading promotions

I went to foschini in Durban Cbd in West street. I went in there seeking facial products, a lovely lady gladly assisted me, I bought products under a brand that was running a promotion, which clearly stated that if 3 products were purchased and one of the products being a moisturizer, customer was entitled to a free bag. The lady who assisted me questioned her supervisor of the promotion, however she mumbled her response and than removed the signage, I was than told there were no more bags. The bag isn't the issue because it wasn't of priority however why should I not benefit from such promotion because somebody did not do their job and ensure that the signage was removed as soon as they realised the bags were finished. This is to me is false advertising and not consumer centric.