Issues with upstream channel bonding after upgrading to 100/10

I recently upgraded from 50/5 to 100/10. Download speed tests are consistently around 100mbps but I cannot get any result faster than 5mbps for upload. I logged in to my router and saw that I only have 2 bonded channels for upstream. I called Cox and all they did was reset my modem a few times and told me that they will have to send someone out to look at it along with a $75 service charge. 

I have a Zoom 5341j that has had no issues until I upgraded my speed plan. Other than calling back and insist on escalating the issue what can I do?