Sour/Off cake - Disgusting

Yesterday was my son's birthday and we thought why not buy him a nice delicious cake at Limnos Bakery Kuils River, even though he was under the weather (lung infection). Long story short, after opening up the table for the family, I decided to cut a piece of cake for myself (Luckily) and when I took a bite or 2, the cake tasted very very strange. I called my wife and asked her to taste, she immediately said no does not taste right, it's off, it's sour. Then I asked my sister in law who taste buds is very sensitive to these types of things, and she confirmed. My brother in law was so upset that he wanted to drive with me because he said what if my son who is sick had to eat from that cake, thank God he did not. My wife then called and informed them about the cake. When I got to the Bakery the lady (I assume she is a supervisor) said to me these strange words, I apologise for the inconvenience, but the cake was off and I placed it below but it seems that someone placed it on top again and sold it, was not supposed to be sold. I wanted to get so furious at this lady and wanted to utter a few words but I kept my cool. Firstly, if you know that the cake was off, not to be sold, why did you put it with the other cakes that in the fridge or why did you not put a note on the cake or why did you not discard of the cake, why keep it in the same fridge at the fresh ones. I had to drive all the way from Silversands area to Kuils River, which a not nearby to hear this and experience this and then they thought macaroons can make up for it. Never!! that what if will remain in my head for quite some time.