[DrivetrainMalfunction650i]

3rd time taking 650i convertible back to the dealer for DTM. Usually occurs while driving on the freeway, car starts to shake, becomes sluggish then DTM appears on dashboard. Purchased our car from BMW dealer Certified Pre-Owed 10/2014 with 30,000 miles. Started having issues within 10 months. After taking the car in the second time they kept it for 25 days and repaired numerous parts. The car was working fine until we took it for 40,000 mile maintenance. On our way home DTM issue occurred again. Seriously debating on getting a lawyer and returning the car. Worried about safety issue especially since it predominately occurs while driving on the freeway.