Rotten White Star Maize Meal

I am writing this as a very dissatisfied customer. I have been using White star super maize meal for as long as I can remember. But i recently bought 2 10kgs at Shoprite protea glen mall. Thank God my grandmother taught me that one has to sift maize before storing. As I was doing that I found what looked like rotten bits in there How is one suppose to prepare meals with it.