Waste of time

I just wasted an hour at Pick n Pay Byls Bridge doing some grocery shopping that turned out to be more of a frustration then anything else and in the end I left without a purchase..... I bought pick n pay bacon on the buy 3 and get the cheapest free but when I got to the till, I was told that that offer didn't apply to the back bacon I was buying. When I finally proved them wrong, I was told that I should buy the back bacon and get a different type of bacon (a cheaper one) free and the supervisor just proceeded to add back bacon, diced and shoulder bacon to my purchase without asking me. I personally prefer back bacon and I told the supervisor that I only wanted the back bacon to which she now had to go to the store manager to get clarity. The manager then came back and told me that its the cheapest offer promotion and I had to take an item of lower or higher value for the system to work . The system should be able to deduct after the 3rd item of the same make is scanned. Through all of this I was treated poorly and with contempt.