well there are several reasons for this...
1. you may be downloading from a slow server.
2. The wireless router.
3. When you subscribed they did not change your cap or "quota" and so your downloads are the same.
Get rid of the wireless if you don't have a laptop just run a wire... because for maybe 2 hrs of work you get alot of speed and call your place and ask them what your service plan is and what the maximum you are currently set at is. as for slow servers sorry there is nothing you can do...
besides what are you downloading... *cough*BIT TORRENTS*cough* lol j/k