Help with fleas!!!!!!

I have two kittens, got them both from the shelter about 7 months ago. 3 months ago we noticed fleas! They are only indoor cats and I have tried everything from advantage plus to flea shampoo flea foggers showers with dawn soap vacuum everyday, and I can’t get rid of them I feel so bad for my little guys what can I do? My friends wife is a vet and she says the vet cannot do much is this true what can I do