If the whole site is redirected then you either need direct access to the SQL to manually reverse the changes that caused the whole redirect. Or if you have host/super user access and there is another portal/site using the same DNN instance you could log into that other instance and make SQL changes using that sites SQL module access.
If the redirects are not stored in the database but the web.config, then using a super user account on another site in the same install you can make changes to the web.config.
If you only have admin access to the one site then I think you will have to wait for your parent co's IT dept.