Slow internet connection--Inadequate tech support

I am a new customer.  I only have internet service.  My speed requirements are minimal.  25 up and 7-8 down would be fine with me.  I have the Preferred service and a Netgear gateway modem leased from Cox (that should make Cox responsible for some level of tech support for this device, right?).  I use this device exclusively for wifi at home.  I have no ethernet connections.  I am experiencing very slow internet speeds (1-2 down and less than 1 up).  I have had the service about six months.  I am on my fourth Netgear router from Cox.  Every time I have installed a new router the performance goes up to about what is expected for the Preferred level of service, then drops off after about a day or two.  One exception, the first one cox installed failed in one day and a tech came out and replaced it.  That one lasted for six months with slowly deteriorating speeds.  Now I have gone thru two in the last two days and the one I currently have has speeds of about 1 Mbps.  Phone tech support says speeds are fine to the modem.  I am currently hooked up to the ethernet port and see the same degradation in speed as the wireless.  Tech support told me last night that they do not support the Netgear gateway hardware.  They gave me a tech support number for Netgear.  Called that.....guess what they said.  They won't talk to me because I did not buy the device from them.  They said I had to get my support from Cox.  I know I can't supply enough detail for the tech savvy people I see on this forum to help.  I guess I am just looking for a response from a Cox moderator to help me decide what to do next.

By the way, the Cox replacement hardware place is very close to where I live and the guy there says he makes five bucks every time he replaces a piece of Cox hardware, so he doesn't care how many I bring back.  This whole scenario doesn't seem like a good way for Cox to do business.  I'm just sayin...