There is a programme on UK Television at the moment called "Dog Borstal". Big beefy, military-type chaps train very difficult difficult dogs (all sizes) and their owners. They use a plastic bottle with a few pebbles in it, watch the dog carefully and just as it is about to do something/anything naughty they shake the bottle and say firmly (not shout) "No".
I've trained difficult dogs/owners in the past. Never tried that and thought it couldn't possibly work - it's all done for the television, I cried. I tried it with a friend's German Shepherd and West Highland Terrier.
It worked, almost first time, with both. I was gobsmacked
- might be worth a try - and won't cost you anything.