DmttmD

I owned a Mercedes Benz E350 2010 which have a transmission replaced last month. Last Monday, On the way to work the car suddenly shift back to low gear and stuck there. I stop the car and put it back to park position and try to drive and again. This time it gave me an Blind Spot assistant inoperative. I press Ok then another message came up, states that the Pres-safer function is limited. I press Ok again. Then the Check-Engine light went on. I have the car tow back to the dealer so they can tale a look at it. Today, They said something wrong with the transmission so they have to replaced it again. But I have to paid out of pocket about $2600 for a corroded sensor in the back which cost $1900, plus flushing the transmission for other mounting part I forget what it is. But the total cost for flushing transmission and that mounting parts are $700. I did have the transmission flushing done before I have the transmission replaced. My question is: Does the Transmission issue may caused the malfunction of the Blind Spot Assistant sensors system, does it really cost that much ($1900) for replaced just one sensor, and should I have to flushing my transmission again. Thank you for you help

P.Doan