Less Than 30 Days and Fleas Again !

Here it is, less than 30 days of using the new flea medication called Vectra, and my dogs have fleas again. Now, its not like they are outdoors all the time, but geez, I am so tired of fighting off fleas. I have tried just about everything, but now I am wondering if those garlic tablets offer any help? What about the vinegar in the water, would that help? I have no clue. Anybody using something that actually works?