Game Baywest False Advertising

Game Baywest I understand that its black Friday etc, but 1st thing on the 2nd day of the sale no stock and Managers are not interested at all in assisting. 6 pack milks are sold out but the same brand milk has 2 shelves fully stocked but individually. When I asked can I not take 6 to make up a six pack I was told "NO it doesn't work like that". So why when you have the stock to sell you cannot sell it. The Manager was rather cheeky to say its not his problem as the special has been running for a while but as per printed newspaper special was for 25 Nov - 01 Dec. 2nd Day into the special but no stock. So is this not false advertising?