Thanks Jim, I am coming to the same conclusion. I made the silly mistake of buying an upgrade online which looked authentic as far as I could see. Not the case, the site credential and email exchanges were very detailed, but the SD card arrived in a jiffy bag without any paperwork. The instruction to copy a file sent by email as an add-on didn't work because the SD card was `Read Only', which makes sense. Then they ceased to communicate! The `writing on the wall' was clear: I had been scammed! Fortunately I did not attempt to load it in the car. The credit card company are now chasing matter up. It will be interesting to hear what they say.
For the benefit of others the site calls itself SatNavUpgrade.com. There is also a similar one called SatNavUpgrade.co.uk. Neither are registered at Companies House, or I'll wager, anywhere else.