I believe my kittens were killed by Hartz Milk Replacer

I wish I had known the horrible stories about Hartz Milk Replacer for kittens before I had given it to my babies.I rescued 5 little girls after their mother passed away.I was feeding them milk replacer from my vet,and one afternoon I ran out.So I went to Walmart and bought Hartz precision nutrition milk replacer not knowing that days later I will lose three of my girls.Last Wednesday my girl named Charmin and on Thursday my girl Phyllis were put to sleep.And yesterday afternoon my girl Dottie had to go and be put down also. The symptoms are the same as I have been reading on here. Vomiting,off balance,falling over when trying to walk,unconsciousness,glassy stare,and unresponsive. My vet thought it was hypoplasia not thinking it could of been the milk they were drinking. My babies were 5 weeks old doing great until I fed them that milk. Then yesterday afternoon I thought what if it is the milk. I never in my wildest dreams would of thought I would of found this website,and people with the same thing as I went through. The guilt I feel is unbelievable. Sure you can say I didn’t  know that the milk was gonna kill my babies,but it doesn’t change the fact that the guilt will always be there. Why is this product even allowed to be on the shelves. How many other people will go through what I went through and not realize it is the very product that they thought was gonna help their kittens. Hartz needs to be taught a lesson. If there is anything I can do I am there to help. I don’t want others to suffer like I have.