Sour Milk

I bought Full Cream C***** Milk from Spar in Nigel, the expiration date on the milk gives you 7days until expiry. This is now the 3rd time that I have bought the milk and it is sour the next day. I am highly dissapointed in C***** and Spar for not making sure the best qaulity is sold to customers. Being in the retail business myself this is unacceptable .