Is there a way to change the power levels of a broadband connection yourself?

[Lethn]

So thanks to some ( Polite ) rage posting on the Virgin Media forums I've finally managed to kick one of the support staff into responding and they're saying that it's something to do with the power levels or dBmV which you see in the router status. It's a long shot, but doesn't anyone here know anything about this and whether I could in fact change them myself? Because the support staff are utterly useless I don't want to have to rely on booking an engineer every time something goes wrong if it's a simple matter of changing some values or configuring something in a slightly different way.