My sunroof frame was breaking into pieces and water would leak into the car. I researched the cost of the part and its availability on line. I could order it online for about $246.00 direct from GM (part# 20860270). Seeing that the part would need some expertise in doing the install, I knew it wasn't something I wanted to attempt. So I called the dealership where I bought the car (Geoff Penske) to inquire about setting up an appointment to have the part ordered and installed. I spoke to the parts dept. and they ordered the part and then transferred me to service to set up the installation. We set the appointment for 11/20/2018. I was quoted a price of $380.00 for the same part and $550.00 for installation from the dealer. The dealer supplied me with a loaner car while the repairs where done. About 5 hours after dropping off my car, the dealer called me and told me the work was finished and I could pick up my car. The whole staff was courteous , the work was done professionally and completely on time. I only have 2 complaints. #1) If I could order the part on line for $246.33, why am I charged $380.00 for the part? #2) The technician who did the work did not clean the area of the door sills where he stood for the installation. My car has Cashmere interior and I had greasy footprints on the sills and some carpeting. I will have to have the car's interior shampooed and hope the grease comes off. Overall, I would still recommend the dealership and service department.