Ssangyong Musso automatic box

Hello people. My name is Oscar and 7 months ago I bought a Ssangyong Musso Mod 97 Automatic Box. of Mercedes-Benz 720 721 02 01. Since I bought it I had many problems only with the box but never very serious. Two weeks ago I broke the box and I have to fix it, here is the question ...
someone knows some mechanic of automatic boxes that is good ???? !!!!
And if not where I can get the Mercedes Automatic Box Kit 720 721 02 01 ?????