While filtering your internet experience is illegal in many countries, sometimes ISPs do so without regard for the law (and risk losing "common carrier" status other places).
One possible solution is to change your DNS server to one that will point you to the correct place. To do this in Windows, try the following:
On other platforms you'll have to find out where your DNS settings are and change them accordingly.
Make sure that you note your old settings in case you want to set them back. For more information on using OpenDNS, please see the OpenDNS Wikipedia page.