I have a pair of Spanx and they work well but they're a bit ripped and about a billion years old. They run from below the bust to mid thigh. The one thing I hated about them was that they used to start to come down a bit creating a hideous tyre between bra and Spanx top.
They also seem way more expensive than they used to be.
So can you recommend an alternative pretty please? (I looked at M&S but they seemed rubbish, way too stretchy so didn't pull me in even at a size down.