hello, i have brought my car to a shop where they only service german cars, and they are licensed technicians.. my trans has been doing hard downshifting from 2nd to 1st. so now, they said they have to take my trans computer apart and clean it because its soaked in oil, they have to change my 13 pin connector and change the conductor plate.. at the same time, they have to do a trans flush. the vehicle has 134k right now.. the total they are going to charge me is $750. reasonable? expensive?