I too have had incessent barkers, and know how difficult it can be. Fortunately, I had sucess in the past with an item similar to the "bark repeller". It looked the same but it was blue & I got if from the Harriet Carter catalog.
With my new pup, I tried the "bark off"... what a joke! It did absolutely nothing. I started using a water pistol while saying "shhhhh". I don't want to jinx myself, but it appears to be working.
Now the barking stops as soon as I say ""shhhhhh".