Misled by in-store promotion

Spar has been running a promotion to claim a glass dish with stickers collected we have spent 21000 rands in total for dishes valued at 900 rands for the past month we have been going to the spar at cape quarter Greenpoint observatory and my local which is groote schuur spar to be told they don't have stocks and we should come back the next day then promotion has now ended today and we are still without the dishes we want and the management at all the stores have not tried to give an alternate option which is really disappointing why run these promotions if you cannot honour it this not the first this has happened we are loyal customers and shop daily at spar to be misled