Was sold a rotten supposed to be fresh salad

Went to picknpay yesterday in the late afternoon did a few groceries including two supposed to be fresh salads. One was a cabbage chakalaka salad and the rotten one was a potatoe salad. When I got home the potatoe salad appeared to be boiling when I tasted it it was off. Such incidence are not acceptable at all hence the expiry date was stated the 22 April 2016. I still have the salad in my fridge boiling as it is as proof.