Download speeds depend on many factors, including:
Your distance from the local BT exchange
Local contention ratios
Time of day (later in the day, speeds are usually slower as the USA wakes up)
The condition of your copper wire.
Admittedly 800Kbps (I assume you mean kiloBITS)for an 8Mb connection is not good but all ADSL connections are supplied as "up to ....".
Try speed tests at various times of the day to get an overall/average picture click here