I know what you mean, the speed fluctuates a lot and I don't get always my 1 MB download speed. While listening to European web radios, I'm mostly loose the connection after 1-2 hours and need to reconnect.
Its incredible what we pay for the internet here, with no guaranty on the service. In Mexico and Guatemala you have more reliability, high speed and lower cost.
It can also help for faster performance instead of using the slow default BTL DNS, use OpenDNS (126.96.36.199 and 188.8.131.52) or the Google DNS (184.108.40.206 and 220.127.116.11).