Sour milk

I also do my groceries at president hyper krugersdorp everything month om the 16 i went ro a 3l milk of bosparadys turns two of the th 3 i bought was sour i went back to them to raise the awareness where they gave me two more bottels was supposed to be brand new stock its not even 3 days later amd the milk has lumps im them and is so sour...like ive never had sm issue before witn sour milk in any store yet two times in a matter of days ive received sour milk... like what is going on