Did they by chance walk you through the refresh process? Not just re-sending the signal.
I received an XM subscription for my birthday a couple weeks back and had a similar issue in my 2015 Silverado. Once they tried the re-sending of the signal, they walked me through the re-fresh of the system. It basically was a bunch of steps that I can't recall, but involved turning the truck on for 30 seconds or so, turning it off for 30 seconds, opening the driver door for 60 seconds, etc. After this was done, they re-sent the signal, and it worked. Make sure you do this outside, not in a garage or underground. Call Sirius XM for the step-by-step or chat with them online.