Broken or Not?

Update- I just had the free Memorial Day week again and my hardware was working again so I thought I would repost my unresolved issue from last year. Thanks in advance!

Hi all, the satellite radio in my '09 GMC Acadia just stopped working a few weeks ago with no bumps or damage to the antenna, just one day I could only get Ch0 and Ch1. They tried to refresh probably 7-8 times but couldn't get it to work. They suggested the dealership which I hate but I have become addicted to sirius.xm. $120 later, they told me that the satellite radio module had just stopped working and it would be $400 to replace. Well, I'm not that addicted. Anyway, suddenly the Free Summer event or whatever starts up and I can get the free channels no problem, dialing back and forth between them easily and clearly. So, pardon my ignorance, I'm not an electrical engineer or even an audiophile, but does that make sense? How could I get the free channels through the antenna and processed through the software and playing on my XM button if the radio is broken? Why would these signals be different this week than the ones I usually pay for? Thanks in advance.