A barking collar works well if your dog doesn't like citronella My parents have one for their dog who whines uncontrollably. It was a last resort as nothing else was working and nasty letters from neighbours weren't helping the situation (he is horrendous!). The collar costs quite a bit (close to $200 for memory) but it definitely works.

We tried professional training with my dog and it really helped but you have to be so diligent and persistent and unfortunately, we just didn't keep up with the training as DD kind of took over our lives. Poor excuse, I know! Thankfully he's not really a nuisance barker but when he is, we also use a collar on him. Generally the collar alone is enough to shut him up (it doesn't have to be on!) and we hardly ever use it TBH but having it there sure is handy at times.

Good luck hon. Barking can be very annoying for all those in ear shot!