I bought fresh milk X2 boxes of medium fat milk,when I was on my 3 litre I noticed that the milk is spoilt, went back to the store to report and to get another brand of milk

I bought fresh milk X2 boxes of medium fat milk,when I was on my 3 litre I noticed that the milk is spoilt, went back to the store to report and to get another brand of milk.unfortunately I don't keep grocery slips. I was told because I don't have a slip I was going to be given the same brand, for me to get another brand they need a reference number on the till slip. I got a shock when they told me that they don't have the backup system for their tills like other stores,ShopRite for example. I even called their head office and got the same response, very disappointing shem.soo I left all those litres of milk there and went to ShopRite to get another box.