This might be useful Clara
Clara....I make a paste with soda and a little water. I cover the marble with the paste then covered with saran wrap and taped to seal...leave it for 24 hours, remove the wrap and using a damp clean soft cloth using a little elbow grease if needed. It worked really well for me on marble that was over 150 years. Good luck!
Mayonaise works if you rub it in with a soft cloth.
Bleach on a cloth let sit on the stain over night marble is pourus