Changing out my contour DVR box

I received a notice telling me that my Contour Cable Box was showing a history of failed hard drive sectors.  We have been having problems replaying shows, with occasional freezes, and then spontaneous reboots of the system.  We had held off changing the box out, in order to watch some of the shows we had recorded.  Can I bring my box in to a cable store, change it, and then plug it in myself, or do I need to schedule a cable service call to have Cox do it?  And if the latter, do I have to pay for that call?