Spanx - you can get them in JL or Debenhams. They are magic. I swear by mine for smoothing and holding in, comfy too. They come in black or nude. Mine are to mid thigh and up to the boobs, you can wear your own bra, and no nasty rubber marks or pinching. Mine have a slit at the crotch for peeing, bit of a weird sensation. But if your dress allows, you can pull them up and down without losing any of the fit.