Thanks for the replies. As suggested, I tried wired ethernet. As expected, the results were consistent. It's 2118 and Virgin's network is busy ergo my bandwidth sucks; 2.17mbps measured by speedtest, with no other network activity.
So everything is "working as intended"? The question is how to flag this to VM? Phoning supports connects me with India and some terrible scripted troubleshooting person who is duty bound to follow their flowchart rather than listen to reason, consider the evidence I've gathered here.
Oh and by the way, as we ease out of peak time (22:39 now) I'm expecting bandwidth to return to advertised speeds. Let's check: yep, it's on the increase. Still below par but currently holding at 27 mbps - http://www.speedtest.net/my-result/6094783228.
I have no doubt he is part of the great high utilisation club so ye changing his power levels will do very little more than likely, that being said QAM256 power levels by default should be between -3 and +7 dBmv, however i am fully aware that each CMT has its own set limits and someone with +9dBmv can have no issues at all.. His being -6dBmv and being outside optimal and you not knowing his own CMT actual limits then you are unable to say he is within acceptable range.