Though your local dealership may or may not do it on goodwill RBM of Atlanta replaced the wiring harness on my 92 500E at 120K miles free of charge. Took them nearly two months to get parts and the car turned around but it was all done on goodwill. I doubt MB will do anything for you if you had yours done at an independent but if your dealership did the work they might.
RBM also did the wiring harness on my 95 C36 at 65K miles free of charge. This time parts were onhand (no "slowboat from Germany") and the car turned around in a couple days.
Hope this helps...Lee