Clicks staff unwilling to assist

I purchased hairspray on 18 October at Clicks in North Cape Mall Kimberley. It was advertised as purchase one receive another of same free. however there was only one on the shelf - when i requested if it were possible to get the other when stock arrived i was told no as the spray arrived in packs of five and that the product might be different when they did receive stock. surely they purchase more than one pack? Surely they can provide when they do get stock (rain check). this is not the first time i had experienced bad service from clicks.