Hey peeps, found this very useful pdf on the net.
It informs you on how to determine which sat nav model you have and what version of firmware you are running.
It also tells you how to upgrade to the latest firmware version for your model (www links) but be warned you do this at your own risk, there are different forums reporting sat nav system crashes when attempting to do this.
So this is just for info and it's your responsibility if you choose to upgrade firmware. Red