rotten food and no accountability

I had bought 2.5 white star maize meal from checkers on Wednesday and there was nothing wrong with it, poured it on the mealie container, sunday when I was doing grocery shopping I bought 5kg white star maize mean from Pick and Pay and as I was pouring it in the same container I noticed some ants and worms, I called their customer service and informed them, they only reimbursed me for the product that I bought from their store and the portion that was contaminated by their off product was not reimbursed, they refuse to reimburse me, had I not trusted them and mixed the products of the same kind in the same container I would still have a fresh mealie from checkers, they don't want to account for my spoiled mealie that was ruined by their product, had I known that they sell such products I wouldn't have mixed or even bought from them, lesson learned never shopping at pick n pay if this is how you treat me and not take accountability for your off products. I have been shopping at pnp for my entire life, my family buys groceries there every month but because of this unpleasant experience I would never recommend it or dare shop there I again