Sounds like 2 seperate problems.I would need more info on the problem.These cars had some issues with shifter modules.I would have it scanned with a Star or Xentry scan tool.Only certain shops have these.We do,but may be to far for you.
Well when i was driving on the hwy it shut off, i was able to pull to the side, when i turned the car back on it would't go into gear. Had to get it towed. Another post said that they had the same problem and they put in a ISM control module, whatever that is.
I hope they used a flat bed when towing.The ISM they may mean the steering module.To get the most info I would Get a one day subscription on Mercedes its only $18.00 you can research it. there is a link through www.nastf.org then oem subscritions.I found no info on the ISM causing you problem.You need to get it scanned with a oem tester.We charge $80.00 for the basic test.