ISP Modified Internet Explorer

I needed to install Freeserve Broadband on a system recently. The pc was a new “TIME” system but this came with “Supanet” installed as ISP. When connecting to Supanet a connection interface window is displayed and IE automatically goes to Supanet as home page. The user did not want to use Supanet and the “dialler” window was a complete nuisance.
In cases like this is it possible to restore the “official” Microsoft version of IE and discard the “hacked” version?
Also the ability to repair or uninstall IE (found in Add Remove Programs does not work with these modified versions). Many users install IE from an ISP’s cd and this replaces the “standard” version. Not helpful if one needs to repair the installation!
Any helpful suggestions most welcome.