Expired milk

I bought milk like i usually do at spar . I opened the 1st milk on monday on tuesday it was sour. Open another 1 same thing. I go to spar to show them that the milk which has an expiry date of the 11/12/2017 they tell me about the receipt???????. What am i ? Receipt keeper? I always buy milk there every 2nd day as we use it for cereals then this. The manager is arrogant and doesn't respect consumers . He clearly doesn't know the consumer protection act I use my card to pay avoiding this kind of things. They think i can go back to them for something i didn't buy. Is so shameful that u take the money i dont have . My kids need milk to eat and u making money out of a poor women. I edge those buying from spar to consider when they buy as they have no customer respect