Paid wrong amount

I am angry and atv woolworths and they're crasher. Today I went to buy the cooking at R49. 99 that was fine i even bought 2. Then the is the chicken with the orange sticker. It was R89 now 65 i took it thinking I am paying that amount. Went to shoprite to buy the rest of my groceries got the my money is short. Now I am thinking did I lose it. That cashier didn't even bother to ask if I knew exactly the price all she asked was woolworths card and plastic now. I am up at this time cause I have been re-calculating. Woolworths I want my money back please. Teach ur cash to assist customers. Now i am coming back to give you ur meat i want my money back please. I don't work with meat or shops i am angry