Modem stops working in middle of the night.

I recently returned my tx boxes at the xfinity store. Since then for the past 5 days my modem stops receiving signal in the middle of the night. I have to call customer support and they have to refresh my modem from their side and internet starts working. But the next day it stops working again and I have to call customer service and they have to refresh the modem. This problem started after I returned my tv boxes. I am not sure if the guy at the store removed my xfinity modem from the system.  Xfinity customer service is unable to fix this problem. Seriously thinking about canceling my service and switching to a different provider.