What type of connection do you have? Sattelite, cable, DSL, other?
Go to ww.dslreports.com and do a speed test there, run it a few times during the day so you can get a good average, that will tell you the actuall speeds you are getting. Note that in your contract it probably states that your top speeds are not guaranteed to be there 100%, you can complain, but you may end up out of luck.
If you have satellite, streaming and onling gaming will have issues due to the large amount of delay as the signal is traveling, something called "lag" or "latency". http://en.wikipedia.org/wiki/Network_performance