BMW Differential Problem

Hi,

I recently took my car to the dealership to have my tires replaced and a wheel alignment. After the tires were repaired the dealership took my car for a test drive and noticed a burning smell along with a clunking sound coming from the tires. After another inspection they say that my car now needs a differential replacement. Is there something that could have caused this damage during the test drive? The same dealership had done an inspection a week earlier and found nothing wrong except for the tires.

My car Model is a 2004 BMW X3