Severe Fleas and ticks treatment for strays

I am Marinella Palaganas from Philippines. It started with strays I am feeding outside. Almost 5-6 months I am treating this parasites. Spent every thing I can. And now I am having hard time to buy broadline for all of my rescues. And I can't release some of my TNR because I don't want them to suffer and will transfer to the other cats. Someone donated expensive shampoos, and I bought herbs or any cream and oitment recommended by licensed veterinarian but only broadline healed one of my Rescues. I have more than 40 rescues. Even foods we're struggling everyday. Cents and shares will make a big difference. Thank you💖🙏