Getting much slower speed on the ultimate plan

Hi there, I recently upgraded my internet plan to ultimate. I was not getting the expected speed because of my old crappy modem. So few days earlier I upgraded my modem to Netgear CM500, which is one of the few 16x4 compatible modems listed on cox's website. Oddly enough I'm still not getting the desired speed, and the speed test capped out at ~70 mbps on both speedtest.net and cox's speed test tool. In fact, it's even slower than the speed I was getting on my old modem, which, when lucky, sometimes went up to around 100 mbps. 

Please help.