Continuously getting rancid Pronutro!!!

I am absolutely sick to death of the foul tasting Pronutro I have been getting on a number of occasions. It seems to be the original and banana flavours. There's obviously a serious issue with the manufacturing process which needs urgent review. This is the 6th box I have purchased from different sources and different batch numbers and still the same foul chemical smell. I have used Pronutro since I was a boy but that's it guys no more for me!!!