Sour milk

So i bought the 2L extra shelf life milk on Wednesday last week. Yesterday morning when i wanted to use the milk it was sour and the expiration date on it was 7/11/19.so i went back to spar yesterday and bought another of the same milk. This morning when i wanted to make koffie the milk was soure again ant the expiration dat on the second 2L is only 16/11/19. We pay through our ears for this stuff only for it to be soure the next day. I am highly disappointed in SPAR.