Blower problems of the 2000 SAAB 95

My 2000 SAAB 9-5 has only 39,500 miles. It has lost the ability to heat the drivers side which is a safety concern while driving in the winter. The system can not generate enough heat to melt the ice on the windshield. I had the car diagnosed at the SAAB dealer at the beginning of December. The diagnosis was that a motor shaft in a heater box was broken. Last week I found this shaft on the floor. It has extensive mechanical damage. In my opinion the only explanation is that it was defective when it was installed in the car or the design of the heating system was not done properly.