Since many people have this problem (lately) on early W202 cars, it would seem time and not mileage is probably the thing that causes the most wear and tear on the harness.
It's nice to hear of some higher (relatively) mileage W202 cars. Many owners I meet are older folks that drive 5-8K or so a year. In Canuck-land, the average C-class buyer is about 60, so it's no wonder...
1998 C230 "Black Betty"