got asked for returns of devices that I never received?

I am moving to a new address soon and I also want to change a plan on the Xfinity internet. When I deselected the Xfinity flex box option, there is a warning message says I need to return the flex box which I have never received? I have a Flex box a while year ago and I returned it last year at around this time when I did my last move. I am right now using my own modem and my current apartment has a modem built-in I think, not sure where does the xFi complete listed below come from.