i assume you tested the speed on >1 torrent, and tracker?
you prob get stick in the greedy bunch.
read the blink Terms of agreement
you allowed 4GB up and down total a day. for a total of 3 consecutive days before your being seen as breaking the ToA.
also in the event that you are using the net during peak times, you will get slow down too (peak is 8am-6pm i think)
yes it sucks but we all hadda deal with it.
http://www.blinkbroadband.tt/fairuse.cfm