I don't know if there is anything you can do either regarding the breeder or the former vet.
However, an overbite may never cause any problems, unless you were intending to use the dog for breeding.
I had a rescue cat that had a massive overbite and to start with I was worried that he perhaps could not chew his food properly.
Two days carefully watching him eat, convinced me that he could and did chew anything I gave him (which I may add his size, as he was the largest cat I have ever had, indicated, as he was fully adult when I got him.,
So your dog may never have any problems with chewing or with her teeth.