Bad customer service and false price advertising

I was at the Checkers atterbury value Mart store ,as I doing my regular morning shopping, I took 2Kg Enterprises No pork Polony advertised Buy any 2 and get the cheapest free for R74.99.Then made my way to the Tills.After being in store for over 30 minutes, with A lady called Mari who was very helpful but couldn't authorize as she has no code.She called A lady by the name of Mpho April, who was very rude even another customer explained to them that because of what is advertised on the Fridge,I was not in the wrong.Then Mpho called the Branch Manager (Christopher) who was out of line with his tone of voice.He even said that Mari must just reverse my sale and I should go ahead and lay a complain as he is not scared of me.He even refused to call Head Office as he doesn't take instructions from my kind.Continued to say you can even take pictures I don't care and he had security guards with him.So I paid for the bacon and left the store as he walked away.This is a problem as I always get my daily meal from this store and I work in the same center as well