Toyota — toyota innova crysta 2.8z fumbles

I purchased toyota crysta 2.8z last year, in the month of july 2018. This vehicle has lot of good name in the market
But i am very much disappointed with the performance, the problem which i am facing is, the vehicle
Fumbles when the speed is just above 100 km. The steering of the vehicle starts shivering and it becomes
Very much inconvenient to hold the steering. I showed this to our dealer grace toyota. But even after servicing the performance has not improved. Please let me know where to go.