Well, where on earth do I start to even try and give advice without making it sound that she's killing her pets?
I wouldn't try... I'd make it sound like that's exactly what she's doing, because it is.
That really is awful though. The hard thing about teaching others to properly care for their fish is that they usually think you're nuts for even caring. If they kept a dog or cat in such horrible conditions no one would blame you for giving them some strongly worded advice, but it's like fish aren't even considered pets, but more like decorations.