SPIII has been discontinued as a new model for (getting on for) two years. That notwithstanding the only updates that are free are the Mapsourse Application and the Software updates for the GPS receiver and they are free for life.
Not the maps themselves
To unlock V7 should cost you $150 US not £
Sounds like you have either been mis-informed or you mis-interpreted what you were told. Many have come to the same incorrect assumption due to Mapsource being 3 different things and only 2 being free.
