as you live in Europe, order the leather care set from Harry Wagner, well known among the E32 and E34 drivers.
Here a repair shown on a BMW meeting
http://www.leder-wagner.de/gallery_index.php?gPath=2_3
http://www.leder-wagner.de/articles_...articles_id=10
http://www.leder-wagner.de/Reparatur...ch-pid-47.html
http://www.leder-wagner.de/articles_...articles_id=34
if the colour is black, buy this set
http://www.leder-wagner.de/product_i...products_id=86
in case the colour is another one, send him a small sample of the good leather from under the seat where it is still o.k., size like a coin, and he will mix it to match.
He speaks English, no problem.
I imported already a lot from him for my friends in Japan, and I know him personally from one of the German BMW meetings, he owns an E32 740