Spoilt Milk

Good Day, I purchased 18 litre (3x6 lts) during the Festive period and found that 8 litres were spoilt this morning. I have purchased from Checkers store at Conubia shopping mall ,and long life milk does not go off in a hurry. I cannot take them back to the store as I purchased in December and don't keep my receipt. please advise who can I contact. regards