Guys,
It makes a big difference if your connected to your modem via a good quality network cable, as opposed to using the modem in wireless mode. Of course those with wireless USB type modem/plans have no choice unfortunately.
I have found in the past that the telephone socket contacts become oxidized the more the line is used with high frequencies. As this happens eventually the line seems to all of the sudden slow down. The only way around this is to change the socket every 6 months or give it a going over with WD40 to disolve the oxides!
This extreme circumstance really only happens if you live near the ocean like I did. High Frequency Electricity, copper and salty humid air is not a good combination. I suppose other enviromental conditions could have the same effect.
My current ISP: TPG
Plan: Home Phone + 500gb Premium ADSL2+
Using Speedtest.net
ping: 29ms
DL speed: 13.96 mbps
UL speed: .67 mbps
And that's pretty much how it is everyday.