C28096

i have a 96 c280 that has 256,000 miles and runs great. it has supposedly been rewired by a certified Mercedes technician but there are flaws in the wiring. the reverse light come on when its in reverse or drive. but this isn't the big problem. the car shifts funny. it is okay from 1-3 gears but it still doesn't seem right. it doesn't shift into 4th at high rpms. it stays in 3rd. and when it does shift into 4th it shifts hard. any suggestions? thanks.