Price on app not same as in store???

The last two months I have checked the prices of items on the new app, and then went to buy them in store. Yesterday I checked the price of Long life milk 1L 6 packs- marked R61.99 down from R84.99. When I got to the store, I took 3 boxes, at the till the price was R64.99. I am not someone who complains much about prices, but why does the price differ from the app?? It hasn't previously?? I went on the app and showed the price to the cashier. He called the manager to change pricing. The manager said R64.99 is the price that is on the daily difference and that's that. Wil R9.00 really make Woolies lose so much profit?? I was disgusted with the service received. If their prices aren't equal to the app, then hell, why have an app??