3 week old kitten is riddled with fleas so much it has blood discharge on her fur

I tried using a flea spray twice but it didn't work then I bathed her in soapy kitten shampoo and it didn't work. I tried to comb with a flea comb (the one that has small metal teeth close to each other) and still barely did anything other than plucking out the hair.

When i bathed her the water turned light reddish color.

I called three vets, they told me the below:

First two vet said: soak her in a flea shampoo bath

One vet said: Spray frontline anti flea on her

The last vet told me not to do anything and instead soak her very lightly in water then pince the flea so they can die each one by one.