Contour Service with Old Cisco Receivers

I have been with Cox for over 11 years. I currently have 1 old Cisco 8742HDC box and 2 - Cisco 4742HDC boxes that are just basic HD receivers and 1 Cox mini box. I noticed recently while paying my bill, that I am being charged for 3 Cox Contour boxes. Not sure how long I have been charged for this since I have paperless billing (will be switching to monitor), but my questions is... Should I be charged for 3 Contour boxes when only one has DVR service capability and the other two are just basic HD receivers? It is basically like having 3 minis, but 2 aren't so mini. Just curious on whether I should switch to those mini's to save money or request a refund for the months of charges.TYIA