Just to put a different POV...
There was a poster on here some years ago who got completely ripped to shreds for sending her dog away for training. She was told it would be a disaster, waste of money, make things worse, she was the one who needed to learn etc etc.
She explained that she would be in touch with the trainer through the process, that there was a fairly detailed handover in place with some regular sessions afterwards and ongoing contact.
She still got ripped to shreds. MN just doesn't like board and train.
A friend of mine sent her young dog (working gundog) for board and train, because she was suffering a lot of ill-health and joint issues and wasn't able to train the dog herself. The dog came home happy and confident and ready to go into work. I know this dog, so her being happy etc isn't just hearsay.
I've recently been watching videos of an in-house board and train. The dog has gone from an anxious, overwrought, dog-aggressive mess to living happily with the trainer's dogs, playing happily out of doors, recalling well. Knowing what I know of that trainer, he will ensure a good handover with lots of support.
Sometimes a change of scene and experienced trainer can get through the bad habits and maladaptive learned behaviour and then show the owner how to maintain that. If I ever went down that route, I'd want to speak to previous clients - but it's not something I'd just rule out completely because I didn't like the idea or because it might go wrong.