Heater blower motor stays running. on 1998 Mercedes-Benz SLK230

The heater blower motor stays running even after i shut the car off.I had to pull the blower fuse out to get it to stop.So for now able to drive but no fan for heat or air conditioning.A friend tells me to replace the blower motor but it can get expensive doing a repair by process of elimination.So whats your advise on this problem?

Asked by for the 1998 Mercedes-Benz SLK230