Ultimate package underperforming

I have the ultimate package in Salina, KS that is supposed to be able to do 150M down but am only rarely seeing speeds over 100M. Speed tests mostly come back with 85-90M results and a sustained download of a 6Gig game from Steam tops out at around 104M. This is not shabby, but it is not what others are reporting they are getting with the ultimate account. The speed test on Cox own site will show 80M or so 5 times in a row and then one result at 114M and one at 130M and then right back to the 80s. The faster results are there, but very rare. I am using an SB6141 modem.

I have a gigabit router, gigabit switch, and gigabit NIC in my PC. I have done tests through my router to a computer on the WAN side and can get near a full gigabit through it (878 mb/s sustained for 10 minutes). To do this I put a laptop with an SSD hard drive and a gigabit NIC on one side of the router and my PC with an SSD hard drive and a gigabit NIC through my gigabit switch on the other side and simply copied several large ISO files back and forth. This verifies that my network equipment can do close to a full gigabit.

Is there any hope of Cox addressing the issue or should I just downgrade to the 100M plan? Because if I am only going to get 100M then I only want to pay for that level of service.