Maybe this page shows you what part is broken or missing. I would remove the tail light and you may get a better idea of what to do with it if the bumper cover is actually broken. With the tail light out you can see what may be possible to make a repair of your own without bumper cover replacement. You can see in the parts diagram that it is part #6 that snaps into that bumper section. Watch the video and you will see the area you need to fix.
https://www.gmpartsnow.com/v-2014-ch...omponents-rear