Price on shellf vs Price on the shelf.

Yesterday I took a product off the shelf to purchase that has a clearly marked price on shelf of R59.99, but upon paying reflected a different/more expensive price of R79.99 at the till. The manager refused to give me the price i saw on the shelf as the barcode didnt correspond.... The barcode may not have corresponded however the brand was the same and descriptor was very similar - the entire shelf above that was packed with the product i wanted to purchase with the cheaper price below it? Surely that is false advertising! .The supervisor shrugged it off as human error YES it was a human error that a packer made who works for PNP and hence PNP is responsible to give the product to me at the price I saw on the shelf. - The supervisor had to double check the description to see if it was the actual product because it is so similar. I feel that as a loyal customer to that store they could have handled the situation alot better rather than just shrugging me off after standing in a queue for 15 min and having to wait another 5 before I was attended to for my query. I will not be shopping at that store and will be telling who ever i can about the poor service i received!