Missing item in order not even acknowledged

Up till now I have had no problems with Checkers 60 and use them weekly. On Friday I ordered groceries including a tray of chicken fillet which I needed urgently. The goods arrived, but when I unpacked them there was no chicken though it showed on the app that I had been charged for chicken and chicken had been included in the order, while another unavailable item hadn't. I notified Checkers 60 via the app and gave them a substandard rating but to date have received no response. It is now Monday and still nothing. I am a pensioner and cannot afford to throw nearly fifty Rand away.