I have no experience with dogs, but if you are looking for a positive reinforcement based solution, maybe you could ask
Brenda, who also has Border collies. I don't know much about her interaction with them, but when it comes to horses she is such an inspiration in terms of training in a very systematic, purely positive way, so I guess it will be similar with her dogs (you can see some videos in her
dog video channel). Unfortunately, she does not write here anymore, but perhaps you could simply send her a PM.