Unsatisfactory service

Bought butter on Saturday and used it at night to make sandwiches for me and my husband. On Monday morning when I was about to use the butter again I noticed that it has actually expired in July 2017. Was so furious as I didn't expect it from a company like them. Took the butter back Tuesday morning, good thing I still had my slip as I don't normally keep them. When I got there I approached a guy who was on the floor and I explained the matter and also showed him my slip and the butter itself, he apologised and went to call the manager on duty, and the only thing she said was do you have your slip and would you like a refund or another butter?? That's it nothing else, and the poor man followed me to apologise as he saw how the manager handled the situation. No apology nor an acknowledgement from the manager, her service suck and I don't know she didn't care coz it was a black woman complaining, I wish I didn't have to buy there again, I'm ****ed, just that our 7/11 of over 25 years has moved so we have no other shop near us just that pick n pay.