First treat the seat with the PURATEX Textile Intensive Cleaner, following the instructions precisely. Allow to dry thoroughly, then protect with the PURATEX Textile Impregnator.
Unfortunately, however, if the colour abrasion has already drawn too deeply into the fabric, only the upholstery specialist can help. We would be glad to help you find one close by, Tel. +49 7251 / 9625 0.