"Well it's clear you can't both be right."
Obviously. I'm right and she is wrong.
"If Ann is as egregiously wrong as you claim, that will certainly compromise her sales in the future."
Why? Her core audience is barely literate. She doesn't give a rat's behind about anything but her royalties.
Her core audience includes many people from whom you should be willing to learn. But, apparently, are significantly too arrogant to consider that possibility.