My order had missing items

I orders on PicknPay Gardens (Cape Town) via the MrD app, my order arrived and there were missing items in my package, I have been reporting this and I’m being told to come in store with the receipt of which it’s unfair to me because it’s their negligence that led to this, I’m very far from Gardens and it’s going to cost me now. It was never indicated in the app that the items are out of stock. I paid for everything in full and now I’m being told to come, for what? No I need this to be fixed. #GROC***