Williamson Buick GMC

I dropped my vehicle off for its first service at 7:30 AM on Friday morning August 9th. It’s a GMC Sierra 2500 HD. I asked for the DEF fluid to be topped off and was told it would be covered by the warranty. I received a call at about 12 noon stating that the vehicle was completed but while it was driven through the car wash the passenger side mirror was damaged and will have to be replaced. I was also told that I could come and pick up the vehicle. Since I did not want to see my vehicle damaged and I did not want to be driving the vehicle with a broken mirror I told them to keep it until the repairs were completed. On Monday afternoon I received a call that the vehicle was ready and they would send a courtesy vehicle to pick me up. When I arrived I went to the cashier and was given the keys to my truck. Upon starting the truck I noticed the check engine light was on and the DEF fuel was not topped off. I went back to the service desk and the service manager came to discuss the issues with me. I was told that the DEF fluid was not covered but he offered to give me two bottles of fluid and he topped it up himself. He was very accommodating. He did a computer diagnostic and indicated that the problem appears to be a sensor. He then took the vehicle back to the shop to sort out the problem. After a while he came back with the truck and indicated that the problem was fixed and the reason for the fault was that the sensor is in the passenger mirror and it was not connected when the mirror was replaced. My concerns are why have associates drive customers vehicles when they are not familiar with these large trucks? Why didn’t the service advisor call me and tell me that the DEF fluid was not covered? Why give a customer a vehicle without verifying that everything was functional and that no faults are evident?