I have a miniature Shnauzer who recently turned nine. In his younger days, we...well, we didn't bother training him that well, and now he's had a barking problem for a long time, but it seems like it's gotten worse towards strangers lately. We tried a shock collar, and he figured out how to push it with his paws so that it didn't shock him anymore...thought it was a mistake first time, put it back on right, repeated multiple times... I've tried just ignoring him, holding his muzzle shut, etc. What can I do? Is it too late?