hi guys major problems and need help please 1997 w202 c200 (5 speed auto)just driven 140 miles to manchester airport to collect son off his honeymoon drove fine going but coming back if it changed down a gear it held in that gear after about 100 miles it would barely do 50 mph when i pulled over to havea look it didnt want to pull away and it wouldnt change up the box i let it cool down and it was ok for about 2 miles then it was the same again aa recovered me off the motorway i waited for one and a half hours for the aa mechanic to say he couldnt help but he would follow me home about 2 miles and it went again it starts drives but its not changing gears but on the occasion it didchange there was no acceleration can anyone help please