I've black and white lino in the kitchen. It was a cheap offcut and is now badly stained. Although it's smooth it's almost as if it's ingrained. I've tried scrubbing with bleach, but the marks remained. What else can I use? Can't afford to replace it at the moment, but it permanently looks dirty even when freshly mopped. It's not stuff that's spilt, more like from shoes/slippers. Anyone else had this? If so how did you remove the marks?