Poor customer service

Yesterday I bought small groceries at woolworths Attlyn Shopping Centre when I was outside taking the groceries to my sister who sent me she told me she wanted 2 x 2kg brown sugar I then returned to the store. I requested them to take back the carrots I have bought so I can buy the 2kg brown sugar. Brenda refused to assist me and the manager when he/she was called refused to come. I couldn't take the carrots I left it because it was not needed my sister wanted the Sugar. They couldn't even show me on paper or somewhere that I couldn't return the item they couldn't even let me speak with someone at head office.