I've been meaning to get back to you Gill uses "Multi-use cleaning eraser" It's a four pack that comes in a purple and blue box. They're small white sponges that bring them back to white beautifully.
Nope... Nix...nada...
no magic in those sponges.... Didn't work to get the stains off (and yes, the stain came back again during the week). Will try the degreaser trick next!