Haha what a loads of balls... This sound to me that providers are playing a massive con.. One way for you to check is as follows: Install stb emu on a supported device, change the MAC of the stb emu to match that of your mag box, enter the url that you have into stb emu, ensuring you now turn of your mag, save the setting in stb emu and see if it connects. If stb emu fails to connect then the url has been cut or if its say blocked then it is your provider.
Point to note.
There is no way that the makers of the mag device have blocked your provider. This would mean that they would have to issue an updated firmware image which would contain a list of blocked urls.