Audi A4 2.0tdi avant 2007
I've used the satnav regularly for past 5 years but over past few weeks I've been getting a problem - message pops up 'unable to read disc'.
Sometimes the problem goes if I take disc out and then replace, other times it carries on with same issue. I've also changed the disc to a newer version but still same problem.
Couple of questions to pose:
- Do I need a whole new unit? If so, where do I get one from and who do I get to fit it?
- does something just need cleaning? If so, how do I do this?

Many thanks