What correction have you used for the barking? It is obviously not working. You will likely have to step it up.
So far we have only tried what our class instructor has told us, which was to grab hold of snout
We had a reactive WL GSD in our beginner I class in the beginning of October. It took a strong pop on the prong to get him to stop barking at everything (other dogs, people, his reflection in the mirrors, dust floating in the air).
As stated he only barks in class, and we were advised against the prong color.
Now he's getting ready to graduate from his second set of classes (beginner II) and is a model dog. He needed his owner to understand that positive only wasn't going to work on him. He needed his owner to step up and be a leader who would enforce their rules and MAKE him do what she wanted him to.
Hopefully we will get there very soon
Does her dog not like other dogs, or does her dog not like rude dogs getting in his face? Rude dogs with clueless owner that let them get in each others' faces is pretty common on the first day. Neither would bother me though. Dogs don't have to like other dogs. It's a training class, not a dog park. The dog's shouldn't be interacting with each other anyway and shouldn't be within leash reach of each other. I just spent the weekend with a GSD that WILL NOT tolerate other dogs being jerks and getting in her space. Does not mean she didn't deserve to be in the top 10 (all-breeds) rally standings and shouldn't have been out trialing. Her own just makes sure to let others know to respect her space.
No dogs are getting in her dogs face, she told us her dog is not friendly and keep our dogs away. Her dog is a Dalmation