Dissapointed loyal customer

Since this store opened up in Mitchells Plain ive been a loyal customer, two weeks ago i did my mothly shopping of which i do every month, i spend up to r800 to r1100 on a monthly basis, this time around i bought a 6 pack parmalat milk tray right, not knowing that i would need to go back to the store with a query i throw the receipt away. They sold me milk from May 2020 when i opened the milk it went all sour already, i called the store after calling a few times, with bad customer service as they passed the phone from one worker to the next with no luck of speaking to a Manager. they said i needed a receipt, i told them i am a loyal customer and would like my milk changed for a fresh 6pack. Eventually when i went to the store they wouldn't help me without a receipt. I am very disappointed