Her E does nothing on its own. Sure, she stuns you, but only for a second, and it does very little damage on its own. If you understand the rest of her kit, then her E is a death sentence for her if she uses it to engage.
As for her R, it's supposed to be unfair. That's the way it was designed, to give her the advantage and keep you from running. In a 1v1, you can still beat her if you all-in stronger than her or have a fair amount of CC, but a squishy will most likely die to it -- imagine a Darius being in your face, or an Irelia / Diana being on top of you, same idea. Her R is VERY short ranged, so just don't be near her and she can't even cast it. If she uses her E into her ult, then just CC her and kite her until it fades, and she can't do anything about it.