I do a lot of sisal and because of that I field a lot of sisal related questions from board users. Some of the questions I am asked are regarding wool or synthetic carpets that are called "sisal" because of the weave. These are treated differently than a true sisal, so make sure of the fiber content.
If it is a true sisal, I have had some moderate success using reducers. I would stay away from oxidizers on sisal. Email me or call me if you would like more details.
Jose Smith