Lactalis and their rotten ways!!

I bought 2 six pack boxes of milk from Checkers, Westville mall in Durban only to find that one of the milk cartons had sour milk in it. All the other five were just fine. all had an expiry date of 27/09/2025 What kind of health hazards are being creating here?!?! How does something like this happen!!!? I need answers because this milk was for children's cereal in the morning. I sent an email to the company : 27 April 2025. got a lame response from Brenda Masa (6 May 2025) saying that they tried to call me but i dint respond. I emailed her back and she still hasn't rep****.