Rotten food sold in boxer

I purchased 10kg maize meal at boxer superstore. When I come back from work I found that my daughter opened the bag of maize and cooked porridge for her little brother. When I took the maize from it's bag to the bucket I found that the maize is spoiled inside and it has formed some black rocks. I send them an email and they did not even apologize they only said I must forward pictures and proof of purchase. I have been waiting since then and no one has contacted me so far. We have recently witnessed people dying from eating food that have expired and now boxer has joined in serving us poison and does not want to take accountability