False adverti*****t on their shelves

I'm so irritated , I took 1 litre juice with the price of R11.95 on the shelve, when i get to the tills their juice scans R16 , and they trying to shift blame acting as if I'm the crazy one, supervisor went and came back with a juice telling me thats the juice for 11, cause codes are different , funny the juice i took was with that price... as a regular customer I'm not happy never mind the R5 difference I'm worried how many customers are they cheating, I Spoke to the Manager Tau on the phone his even worse he dont seem to be understanding my frustration, it's not my fault their machandisers are not putting prices on the right item, and its not my duty to compare barcodes when I do my shopping, I will make sure I expose the supermarket to warn other people who don't checktheir slips when paying...