It will be difficult to get this seed junkie to eat a healthier diet but it can be done but it will take time, lots of it.
Keep offering the veggies and fruits, offer different ones and in different ways as some prefer certain ones certain ways, sometimes they will ignore them and finally one day will try them so keep at it.
Some here have had success with eating the foods in front of your bird to show them you are enjoying them, they are like children who see you eating something and they want what you have. A few have commented that the pellets didn't taste half bad.
If she is dumping the whole dish you may have to get several food dishes that you attach to the side of the cage that she cannot dump, she might pick them up with her beak one by one and throw them out but the main thing is to keep trying.
A lot of people especially avian vets do recommend Harrisons pellets but there are a lot of other brands that are almost as good that maybe one of them she will eat, they all would provide nutritional value.