Getting rid fleas from dogs is beating me

Usually it's beating people because only the dog is being treated. Most of the fleas aren't on the dog at all, they're eggs and larvae in the carpet and bedding, and they keep hatching for weeks. So: a proper vet treatment for the dog (the supermarket stuff is often weak), and treat every pet in the house at the same time. Wash all the bedding hot, vacuum every day for a few weeks and empty the vacuum outside. Expect to still see the odd flea for a month or so as the last ones hatch, that doesn't mean it's failing. Also never put a dog flea product on a cat, some of them are toxic to cats.