Thanks so much for your patience whilst we are looking in to this fault.
Just to give you an update, the teams have been working on this and we hope to have a resolution soon.
As a work around we are able to add a device change for you which will allow you to register the device however as soon as you log out, you will get the same error again. To get the change added, please give us a call on 150 / 0345 454 1111 and follow the options to speak to the Broadband Faults team.
I know this isn't the best solution but it is only a work around until we can get things back to normal for you.