Gear damage at 120,000km

Hello, would have a question. My S-Class (S500) has only been in trouble since I bought it (8 months ago). Every month it is in the workshop. A new “small” problem which costs about 1000 EUR. 2 months ago he was at the service now, and now at 120000km he has a gearbox damage. Mercedes (Salzburg) refuses to pay anything, as a replacement car a SMART was offered. Very nice or … friendly they would drive the 1800km (with The seller (Hartberg) would pay 680 EUR. The damage is only 7000 EUR !!!! Dear people, you have already had experiences with lawyer or other. In the car has been put since purchase about 4000, 2 broken cat., air suspension, and and and and I don’t see absoulut, which one pays with a luxury limusine, which already I believe enough, a fortune for reperatures. lg jasmin