Paying for 2 gig and getting 136mb-158mb download speeds

Cox has nothing to do with this, it's normal for WiFi! If you are using a device, that is connected over 2.4 ghz, then the speeds you are seeing are absolutely correct If however you are on a WiFi 6 device, with all connections made properly, you should be seeing faster speeds. There are a lot of things that affect WiFi, not just distance, but EMI and RF interference, and the solidity of objects between the transmitter and the receiver. If it's all open air, it makes things easier and then you may be seeing fantastic speeds, if it's cinderblock walls and dense objects like a washer and dryer, then you may be seeing SQUAT for speed. 

So, to be able to help, and maybe get you some faster speeds, What router are you using, what device are you using, and can you test using a computer connected with a 2.5 or 10 gbps Ethernet connection? Are you on 2.4 or 5ghz?

Hi, welcome to the Cox family. We want to get to the bottom this for you. Please send us an email at cox.help@cox.com with your full name, address and description of problem, so that we can get your services working the way that they should. 

I'm paying for 500Mbps and I get less than 100Mbps. I have reached out to customer support so many times it's unbelievable. All they will do is tell you to pay for a new cox router (even if the one they gave you supports gigabit) or tell you to pay for a faster service, as if the one you already have sucks enough.