The 'box' you refer to is called a 'wall socket' on VM's website (so, if you can ever get through, you'll know what to call it when you speak to them). However only VM will know whether or not the old wall socket is still connected up or not. (It might well be though, as VM would have had to send an engineer to disconnect it. If you've given them no reason to do so, they've probably never bothered to get anyone to do the job).
The quickest way to get an answer to your question though is probably just to use the 'suck it and see' approach. Simply disconnect the superhub from its existing location and try it in the alternative one. You don't need to plug everything into the system (such as your TV or landline phone). Just check, by using your mobile phone, tablet or laptop, whether you've still got wi-fi or not. If you have, the wall socket remains 'live'.