hi i also have a gsd called charlie, im really sorry u have problems and i just wondered if u use a choke chain. i do and find when charlie is about to do something i dont want ie run after a dog or go to far a head, i rattle the chain and he stops in his tracks. a trainer i no told me whilst training your dog if he dosent do as his told throw the choke chain at his feet and sooner or later he will realise that as a command not to do as he likes. and i can say it works. charlie had a habit of when chasing other dogs he would go to grab them, and being a gsd other owners didnt like it and called him aggresive. a rattle of his chain and he dosent do it. hope its a helpful suggestion. beautuiful dogs by the way.