DVR

The hardware fee should be the $8.50/mo you are already paying

And the DVR Service fee should be an additional $9.99/mo or $11.99/mo (depending on market)
There should not be any fee to turn on DVR Service, if they do, dispute it and get it taken off the bill.
http://ww2.cox.com/residential/tv/prices.cox

Cox Arizona stopped allowing the use of a DVR as a "Set-top-Box only"  on December 1st 2012, and gave notice that if you did not exchange a DVR for a regular STB within 30 days, Cox would start charging you the extra DVR Service fee anyway.  So check your bill to make sure there is not already a charge for "DVR Service"

I can have somebody in our sales team review your account to see what options you have if you like.  Just email us with your account details and contact info at cox.help@cox.com.