Columbus Infotainment - Sat Nav & Phone not working. Juke Box files are corrupt

Hi,

The issues in the title happened a couple of weeks before my 2016 Superb Estate went in for a service. The dealer apparently spent 3 hours trying to rectify this problem but as there was no fault appeared when they ran the diagnosis, there only suggestion was a new unit. At least they didn't charge for their time.
I have the 2 part Columbus, with the multimedia head unit in the glove box. 

Radio and sd card both work fine.

I thought that as the Juke box files were corrupt and the maps database wasn't readable, I could simply reinstall the downloaded maps from the portal. The files on the sd card were recognised but the process quickly stalled.

I now think that the Hard drive has failed, and I thought after some useful thoughts on HD replacement on the previous Columbus system I would give it a go.

My question is can this be done, and is the HD in the display module or the multmedia unit?

Thanks for any help that can be offered.

A replacement multimedia unit seems to be around £450 from car breakers.