Newly purchased modem registered to another customer?

So this has been a whole thing leading up to this point. Basically I have frequent internet drops lasting anywhere from a couple of seconds to several minutes (that could be a whole other post) and in a last ditch troubleshooting effort, before a tech is visit next week, I purchased a new modem to replace an older Netgear CM500 that I also own.  From amazon I bought a Hitron CODA56 DOCSIS3.1 modem to support the 1.2gbps speeds I recently found out I was paying for.  Loaded up the xfinity app to activate the modem and it would not accept the MAC address.  I was connected to support via text where ultimately they tell me the modem is refurbished and currently registered to another customer, and advised that I return the modem, which I did.

Today I went to Best Buy and purchased and Arris S33 and the same story. Couldn't activate through the app, connected to support and after 30is minutes was disconnected.  Then I was connected to another person where I had to explain everything again, only to be told 30minutes later that the modem cannot be activated. When I asked if it was registered to another customer he said "yes, you should try contacting the manufacturer."  I explained to the gentleman that this same exact thing happened last week with a different modem, from a different manufacturer, purchased from a different business, and it must be an error on xfinity's part but I got literally nowhere with him.

Is this any sort of known issue? I don't know what to do at this point.  The support people are not very helpful and they constantly apologize in the course of normal conversation.

EDIT: Okay now this is getting ridiculous. They keep marking my replies as private. Nobody from xFinity has reached out to try and help resolve this issue. After giving them nearly a full year's wages (after taxes) in the time I have been a subscriber, this is how you treat your customers in the end.