Oow i can soooo relate to this with my Jess it was horrendous and like you asked on here and everywhere for advice as she was cutting through our skin, she bit and ripped holes in everysingle pair of jeans my OH owns (guess what he's getting for christmas) and i tried the whole lot!!
The one and only thing i didnt try throughout all of this was what has now worked fantastically for me.
I simply went to Wilkos bought 3 lovely looking tins, 1/4 filled them with gravel stones from our garden.Placed them in different rooms so they would be to hand when she kicked off! Every time she got on one i just rattled the tin (one sharp shake) and omg it worked, she backed off, and now i only have to touch the tin and she stops anything naughty, people had advised this but it was actually the last thing i had tried. she is coming up to 6 months and our arms and legs have healed up nicely hahaha, this worked for us, may not for you but give it a try because it was like a bl**dy miracle for us and she is much much better now. Loads of us go through this as i keep seeing this question being asked, i thought my pup was the only one, so you are not alone and it will stop in the end, my OH was like yours too, very unimpressed, so good luck hope it works for you, boy these puppies can be naughty hahah but gosh dont we love them xx
Annette & the very naughty Jess x