gas gauge frequently goes blank or illumination is reversed

The illuminated gas gauge either goes blank or shows reverse illumination. The bars that should be dark when the gas level decreases become illuminated and the bars that should be bright to indicate gas level go dark. The gauge becomes a "negative" of how it should look. Dealer/service department would not even look at the problem, claiming they "have no idea" what it could be. It's one thing to have a lemon, it's something else when the company makes no effort to correct their defective product.