That’s a relief!!! Thank you for your response!
Sorry I wasn’t clear in providing info. The broadband wireless device actually is the router. It’s the same device you would use for a laptop while traveling, because we do not have access to Comcast (too far out in the country). The Mac is the only computer in the house other than the disconnected and powered-off HP. I can see how many devices are connected to the router from its control panel, and it’s always just one device.
I will go ahead and ask to have my IP address removed from the blacklists and keep looking for another source of data usage.
Thanks, again!!