VW Crafter gear problems and high consumption

Hello everyone, I spent 75,000,-€ and bought me a fully equipped crafter. Instead of the DSG transmission is something else installed which allowed itself to be driven very funny after 4 weeks. No workshop can help me and on the letter from VW to the contractual partners it says „no repair possible „. The stupid is also, that a side effect the consumption thus lies with over 20 liters of normal driving on the highway. Does anyone have a meaningful idea?? With kind regards