Expiring food on shelf and having worm

I bought jungle oat at makro (vanderbijlpark) on the 06 Nov 17 and when i get home and opening it, it was having the worms when i check the expiring date it was due (BB October 2017). Therefore my question why such things are still kept on shelves and this is not the first time i once bought movate same makro and was having the same issue.