Error Code XRE-00250

I have 3 TV boxes.  Over the past 4 days I've gotten the error code XRE-00250 4 times.  It has happened once with 2 boxes and twice with one box.  THey tell me the code for a box hasn't been added to my account, although I've at times had all 3 boxes working.  Every time I report this the agent want's to change my plan.  This is getting a little frustrating.