DEADLY HARTZ PRODUCT

I treated 4 cats with Hartz Flea and Tick powder within the last month. The one who got the most powder, Wobbles, a beautiful black kitty disappeared without a trace, most likely dying in agony under my house, where I can’t reach, as she never left the yard, EVER. She was deaf (she became deaf after being treated for ear mites 2 years previously, at the vet!) and only roamed about 10 feet into the yard and then back into the house. Minnie sickened for a week and died from kidney failure yesterday-Minnie, a 4 year old little tiger Manx, who loved to sit in the sun and beg for her ears and back to be scratched, and Cleo, who is now sickening and suffering from weightloss, salivation, lethargy and inappetence. Cleo, a pretty golden tiger cat is sick and I can’t afford to get her to the vet after spending over $200 on trying to save Minnie. There is no one to help me save her!!! And Inky, who I gave a bath to just a couple days after treating since she was scratching more with the powder on her than she did without it. But now Inky is COVERED with scabs and is losing some hair. I treated her with Frontline, two days ago,  hoping that it will help relieve what I hope is flea allergy and NOT a reaction to that deadly podwer. I hope that I haven’t poisoned her further by using two products. What can I do????
Hartz needs to pay in every way for what they’ve done to our pets!!!