Bad service and poor quality products

On the 28th of September my sister purchased, amongst other items, 2 trays of eggs. The first tray was consumed without any issues. During this week as they started using the second tray, they noticed that some of the eggs were rotten and even the shells were starting to change colour. Understandably so, she did not see a reason to keep the receipt as you cannot expect to experience a problem 3 weeks after purchasing a product. Also we have been using the same store for years and we have never experienced such a problem before.

She attempted to return the tray today. She spoke to the store manager and one of the cashiers, whose names she did not obtain. They took the defective tray but they refused to exchange or refund her for it as they said that tray has passed it's expiry date which was on the 18th of this much. I reported the matter to the customer care and I still haven't received a response.