I have a Mercedes 500s which has had numerous problems with electric. So far I have replaced the 2 sam units, alternator, battery, radio / sat nav and other parts as well and thought I had cured the battery drain but alas no. Now in total despair, as I do not know what to do next. Have had a vehicle electrician look at it who was about as much use as a handbrake on a canoe!! If there is any one who may be able to give me some sensible advice, I would be extremely grateful.