Bought food that has not expired yet, but was off.

I bought a lot of goods on the 25 of May. Cooked on the 26 and made a nice pasta dish. I dished up and when tasting the mushrooms it tasted bitter and sour. The taste was unspeakable bad. When I went to spar. They said they can only assist me if I bring a slip. But the pass due date was the 27th of May. I have the time and till nr of purchase. They did not even try to assist. Even though I know they can. I am so unhappy with the quality of fresh food and service of the management. This is the second time I have had an inconvenience with the same spar.