Okay, I'm lost also. Just what could your dog possibly have to learn? You dog did absolutely nothing wrong!!! The other dogs there have something to learn and I don't see why your dog should be the guinea pig, so to speak. Perhaps you could speak to this lady again and see what it is she thinks your dog should learn from this.
If there is another place you could take your dog to, do it. Where you take her now just doesn't seem safe anymore for your precious dog. I definitely wouldn't take the chance.