I am having a difficult time removing a coffee stain that has been there a while in a carpet mat. I have used Folex with a bissell LGM, tried steam, vinegar, Duragloss carpet cleaner, APC, and a tannin remover, with a brush and shop vac and towels. A little came out but not what I was hoping for a lot better. It is a gray colored mat so the stain is not a light tan color. I would be thankful for any suggestions. The only thing I have not tried at this point is baking soda and hydrogen peroxide, although the Pro's Choice tannin/stain remover does have peroxide in it.