For service and parts needs, visit your dealer. You will receive genuine GM parts and GM-trained and supported service people.
Genuine GM parts have one of these marks:

Vehicle Care
California Proposition 65 WarningInstallation Procedure
Remove rear end upper panel extension (1) from service part.
Cut
Cut the body side inner panel in corresponding locations to fit the
remaining original panel. The sectioning joint should be trimmed to
allow a gap of one-and-one-half-times the metal thickness at the sectioni ...
Headlining Trim Panel Replacement (Without Sunroof)
Warning: Do not attempt to repair or alter the head impact
energy-absorbing material glued to the headliner or to the garnish
trims. If the material is damaged, replace the headliner and/or the garnish
trim. Failure to do so could result in personal injury.
Caution: If a vehicle is equip ...
Roof
Sunroof
The sunroof only operates when the ignition is in ON/RUN or ACC/ ACCESSORY, or
when Retained Accessory Power (RAP) is active.
To open or close the sunroof, press the open or close sunroof switch (1) to the
first detent position.
To express open or close the sunroof with the safety f ...