Well, it's still true that the C-7 was not released until 2020, so whatever you ordered in 2019 wasn't that. 
In December of 2019, you probably got a C-5. If your Amazon order is showing that now, it's because the listing remained the same (ASIN-wise, or however they are associated) and the name was simply updated when the listing was stocked with the new models.
Still, not sure why you'd be having issues with the C-7 arter all the updates. You're probably well out of warranty at this point, but you could always submit a claim on support.hubitat.com just to see if they're still interested.
