SB8600 slow speeds

I have the same model of modem.  I had a tech at my house for two hours last night 10/1/19.  I'm seeing errors on my channels on my modem.   I have gigablast service.  I'm having buffering and freezes.  Tech had me take my modem out to the street pedestal and directly connect to the ped port.  I was getting the same errors there.  I told him the issue must be up the line from my house.  He kept telling me it was a cabling issue.  I didn't disagree but it isn't at my house.  I proved this by hooking my modem up at the ped.  He then cut off and re-terminated all the cable ends at my house.  There was no change still getting errors.  He then calls another tech and he tells me it is a wireless issue in my house.   Physical errors on my modem have nothing to do with my wireless.  I have been a network engineer for over 25 years.  How do I get this issue resolved.  I have been a cox customer for almost 20 years.  When tech left he said he would write an informational ticket for maintenance.  I'm not sure what that means but I still don't have the quality service I'm paying for.